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To protect my SDR UHF receivers on hilltop sites, I needed some filtering to reject local FM broadcast and repeaters.
I looked on Aliexpress what bandpass filters were available. Most of them are SAW filters.
Here are the results of my findings and testings.
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Here is the description of a simple capacitance and inductance meter, easy to build, based around a PIC microcontroler. Simplicity does not mean poor characteristics. The precision is very good and even better than many commercial LCmeter !
The original description has been done by Phil Rice VK3BHR on his pages. I only did adapt it to my needs.
Here are the main characteristics :
- measures from 0 to 838 nF and 0 to 83.88mH.
- precision +/- 1%
- printed board eliminating any connecting wires.
- use of common case (at least here in Europe).
- use of common components.
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Voici un simulateur pour le populaire coupleur d'antenne en T avec capacités série et inductance parallèle. Les trois boutons au bas du dessin permettent d'ajuster les trois composants. Ils peuvent être réglés en déplaçant la souris sur un bouton, en cliquant et en maintenant le bouton gauche de la souris appuyé et en faisant tourner le curseur autour du bouton. Le bouton devrait alors tourner et faire varier la valeur du composant choisi. Les boutons des condensateurs ont une course de 10 tours et la self 30.
| No java |  |
Le ROS est affiché simultanément de manière digitale en haut à gauche du "coupleur" ainsi qu'analogiquement sur le ROS-mètre. La perte provoquée par le coupleur est affichée en pourcentage par rapport à la puissance d'entrée ainsi qu'en dB. En cliquant sur le bouton "Autotune", l'ordinateur calculera la valeur exacte des composants qui adapteraient parfaitement la charge en limitant au minimum la perte dans le coupleur en supposant que les condensateurs variables ont un Q nettement plus élevé que la self.
L'algorithme de calcul Autotune tente de minimiser la valeur de l'inductance à utiliser en commençant par essayer de trouver un accord en affectant une valeur maximum à un des condensateurs variable, puis si cela échoue, il essaye chacun des composants avec sa valeur actuelle. Si aucun accord initial n'est trouvé, il abandonne et affiche "Tune failed" dans le panneau des messages. Si un accord initial est trouvé, il effectue une recherche dichotomique entre la valeur de départ de l'inductance et zéro afin de trouver la valeur minimum de l'inductance pour un accord.
Notez qu'il est simple de programmer un algorithme qui trouve le minimum de perte, alors que nos coupleurs n'ont pas d'indicateur de perte, une règle comme "trouver un accord avec un minimum de self" est bien plus utile. Dans tous les cas, le Q des véritables composants varient pendant qu'ils sont ajustés.
Le bouton Set Up vous permet de changer la valeur maximum des trois composants et leurs Q. Initialement les condensateurs ont une valeur de 250pF, un Q de 2000 et la self une valeur de 30 uH et un Q de 100.
Les trois champs à droite vous permettent de changer la charge et la fréquence en MHz.
Une façon d'utiliser cette applet est de sélectionner une valeur de résistance et réactance de la charge, puis d'ajuster les boutons pour trouver une adaptation, comme vous le feriez avec une vrai coupleur. Notez le pourcentage de pertes dans le coupleur pour votre réglage et cliquez ensuite le bouton "Autotune" et vérifiez si l'ordinateur a trouvé un meilleur réglage.
Veuillez prendre note que si vous cherchez un logiciel pour déterminer les valeurs optimums des composants d'un coupleur en T, vous devriez chercher ailleurs !
Pour utiliser ce logiciel localement sur votre ordinateur, téléchargez le fichier tuner.jar et le fichier que vous visualisez actuellement tuner.html et copiez les dans le répertoire de votre choix, puis visualisez le fichier tuner.html à l'aide de votre navigateur.
Le code source Java de l'applet est distribuée sous licence GNU general public. la source est disponible dans l'archive tunersrc.zip.
La page de l'auteur est disponible ici. Vous y trouverez quantité d'informations intéressantes d'un niveau technique parfois élevé !
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While building up my remote station, i was looking for a solution to control one or 2 azimuth only rotators via the Internet. There are several solutions and i finally adopted the K3NG rotator project i already used for a rotator controller connected via USB to my computer. |
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Having recently acquired this small VHF/UHF UV-998 dual-band mobile transceiver from LEIXEN, here are some informations. Measurements Usage Programming Links This radio is sometimes also named VV-998 ! Please share your own experience with me, so I can improve this page. |
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The orinality of this description is that the tone generation is made by the use of a DDS and not a sine wave generator made with transistors or a special circuit. It also does not use any special and expensive component but only junk box components, or at least cheap ones !
The main characteristics of this generator are :
- Two tone generator 800/ 1000 Hz or 400/2600 Hz (jumper selectable)
- Single tone generator of 1000 Hz
- Ajustable output level, max around 100 mV pp on 600 Ohm, or 35,4 mV eff. in single tone or 25,0 mV eff. in 2 tones
- Spectral purity between 0,3 and 150 kHz > 50dB !
- Distorsion <0,01% (in single tone) !
- Supplied by a 9V battery, consumption 7-8 mA that gives 50 working hours with an alcaline battery.
- Automatic PTT switching at power on.
This circuit has originaly been described by DH7AHN ,adapted and translated by myself for my usage. The original description can be found here
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This page has no pretention and is not a complete description of the vertical antenna, it only is intended to help you understand the most important things about this antenna and to how make it work !
The simplest of all antennas is the vertical, also called the Marconi antenna. It has a quarter wave electrical length and has its base connected to earth.
This antenna vibrates with a intensity node (minimum) at his top, so at a voltage antinode (maximum).
Simple in its operation, it is by cons not the easiest to understand and handle.
Picture : The 1/2 wave antenna and it's equivalent mounted on ground. The missing 1/4 wave can be considered as its image in the ground.
A PERFECT1/4 wave vertical would have at its resonating frequency the following characteristics :- No horizontal radiation
- 5,1 dBi gain
- Maximum radiation at 0°
- Impedance of 36,5 Ohm
- No loss in the grounding system
PERFECT means no loss in the vertical radiating part, no loss in the grounding system (also called counterpoise, by analogy to mechanics)
In these conditions, with a 50 ohm coaxial feedline, you should accept a 1.4 SWR or add a matching system with a quarter wave line ot a LC circuit.
Unfortunately, perfection does not exist...
Consider the same antenna over the best earth that can be found : salt water (i know it's stupid)
The diagram already shows a visible difference :
- Maximum radiating angle : 10°.
- Gain loss : 4,45 dBi
- Impedance 36 Ohm.
This difference is due to a worse soil conductivity.
The same antenna, but this time over a bad soil (city lot). I don't wish that to anybody !
The diagram shows :
- Maximum radiating angle at 28°.
- Important loss : -1,01 dBi
- Impedance 36 Ohm.
We see that the soil nature is very important for this antenna !
The efficiency of a vertical depends not only of the soil nature, but also other factors. Considering losses, the efficiency can be resumed by the formula :
- Losses in the loads (coils, traps, etc...)
- Losses in the ground
In ground losses, we have to consider TWO TYPES of loss :
1) The ground at immediate antenna vicinity in which the current return will be done.
The power applied to the antenna has still not been radiated and the losses are dissipated in the ground and are reducing the radiatiing efficiency of the antenna.
2) The ground all around the antenna over a large number of wave length, typicaly > 2 for a quarter wave vertical.
It is in this part of the ground, called Fresnel zone, that the power radiated by the antenna will be reflected by the soil and will contribute to the reflection efficiency.
We see that for having an efficient vertical antenna, we can act on these 2 factors. If it is almost impossible to influence the second one (you can move to a remote island, water your garden), we can improve the first one in reducing the losses to their minimum.
With a poor ground and in order to have the best current return as possible, we can reduce the losses by placing a certain amount of radials.
These radials can be :
- laid on the ground.
- buried into the soil.
- raised over the groundl.
The first 2 methods are equivalent in terms of performances, except if you are burying the radials too deeply. Depth from a few cm to several tens of cm will not make a big difference.
Brown, Lewis and Epstein in their 1937 studies have shown that in order to obtain a perfect grounding system, 120 radials are needed !
Less radials means worse efficiency, more will not bring an improvement.... A reasonable minimum would be 16 radials of a 1/8 wave length.
Curiously, the number of radials also determines their length. The follwing table gives this relation :
| Nb radials |
4
|
12
|
16
|
24
|
48
|
96
|
120
|
| Length (Lambda) |
0,1
|
0,15
|
0,125
|
0,25
|
0,35
|
0,45
|
0.50
|
In all cases were 120 radials are not possible, it is better to use surelevated radials.
Computer simulations and real-world tests have shown that 6 radials of 0.25 wavelength uniformely disposed around the vertical give the same result as 120 radials of 0.5 wavelength !! Only one radial is altough enough for a good current return, but the antenna will have a certain directivity and a horizontal component.
2 radials are correcting this.
CAUTION, using surelevated radials will lower the impedance down from 36 Ohm to close to 21 Ohm !!
The radials must be tuned in order to reduce the radiation impedance. Their height over ground should be at least 0.03 wavelength, but this heigth depends of the soil quality. The poorer the ground, the higher the radials.
The best would be to elevate the base of the vertical in order to strain the radials at 90° (horizontaly). The higher the antenna, the better the gain.
When all this is not possible, the radials are placed at 45° from the base until they reach the right heigth and the rest will be strained horizontaly.
Some practical hints :
- I'm tuning the radials by pair (in opposite directions) in connecting them like a dipole and with the help of a noise bridge or a VNA placed at the base of the vertical. The important fact is tuning them to the right frequency, not for lowest SWR. Once tuned, they are reconnected at the antenna base.
- Use good insulators at the end of the radials, they have a maximum of voltage at this position. I've seen insulators of several cm taking fire under wet conditions !
- When using plastic insulated wire for the radials, you have to cut them shorter by 4 - 6% as the theoretical length.
- In case of lack of space, you can shorten the radials by placing coils (with some additional losses...) or bend their extremities.
- A vertical works well on a flat, clear and uniform ground.
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During the writing of my beehive monitoring project "Apaguard " using an Arduino UNO, i've been quickly very clode to the SRAM limit...
The Arduino UNO has "only" 2048 bytes of SRAM, which can quickly be filled if no precautions are taken.
Here are a few tricks i used during my writing, which permitted me to save a lot of SRAM and should be used by anyone coding on Arduino.
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During our multi-multi contest operation, we came against a problem while using low band receiving antennas.
There were 3 low band stations, one on 160m, another on 80m and one on 40m.
The problem was simple : how could we share the Beverage antennas on all of these 3 stations ?
The first solution was to split each antenna in 3 directions with coaxial T's and to use a coax switch on each station, so that each station could select a different antenna. That proved to be not very satisfying, the impedance seen by the receivers and antennas were changing a lot depending on the position of the different switches.
DK4VW, Uli told me that the BCC (Bavarian Contest Club) crew was using a Beverage switching box that proved to be very efficient and i began to build such a box with his precious help.
Informations below given with permission of DK4VW.
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To be finished...
Some years ago, i developed my own rotator interface with a PIC 18F452. In a need of another interface, i was unable to find my software sources of this project, lost somewhere in the computer Walhalla ! So, i looked for a finished project to build, and found the K3NG Arduino rotator project.
It looked very complete and having some recent experiences with the Arduino, i decided to give it a try.
What i needed :
- Only azimuth drive
- 2 lines LCD display (as i had several of them)
- Eventualy 2 buttons CW + CCW to drive the rotator
- Running on an Arduino Uno (as i had several)
- Details
- Hits: 8522
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This article is essentially a personal memo, but may be useful to others. AllStarLink is a network of Amateur Radio repeaters, remote base stations and hot spots accessible to each other via Voice over Internet Protocol. It is the software we use on our private TKNet network. Acronyms TX timings RX & TX audio levels settings Language change Sound files GPS.conf for APRS Beacon via crontab |
Acronyms :
ASL: All Star Link
CLI : Command Line Interface
COR : Carrier Operated Relay (Squelch)
CT : Courtesy tone (beeps)
ID : IDentification (voice or CW beacon)
URA : USB Radio Adapter
URI : USB Radio Interface
Note : The procedures below are only for a DUPLEX operation with 25 kHz channel spacing and the use of an interface with a sound card (DSP) and a USB interface as the USB audio interface developed for our TKNet network.
Configuration files :
The main files to modify are rpt.conf, usbradio.conf (or simpleusb.conf), iax.conf, modules.conf, extensions.conf, dnsmgr.conf.
Depending on the type of USB interface and/or type of radio, you have to choose the right interface.
For a radio without pre-emphasis or de-emphasis or without a CTCSS decoder, choose usbradio.conf which uses a DSP and can therefore decode CTCSS and allows more functions.
For a simpler configuration, use simpleusb.conf.
You have to activate only one of these modules in the modules.conf file
Then, you need to determine the node number that will be used depending on the environment. (node to node connection, AllStarLink public server or private server)
The usbradio.conf file contains the "hardware" configuration of the transmitter and receiver used.
Operation of the sound card, simplex, duplex, CTCSS frequencies, various delays, audio filters, pre-emphasis/de-emphasis, PTT status and squelch.
The rpt.conf file contains the node configuration, telemetry (beacons), morse code, audio levels, DTMF commands, etc.
The modules.conf file configures the modules that will be loaded at start-up.
It is necessary to put load in front of the interface type :
load => chan_usbradio.so
The extensions.conf file is used to route incoming connections to the correct node in app_rpt.
The iax.conf file defines how to register a node with the Allstar link node allocation authority, and assigns a context that incoming connections receive so that the statements in extensions.conf can direct the connection to the correct local node. iax.conf contains two sections relevant to app_rpt. The [general] section, and the [radio] section.
The dnsmgr.conf file is used to configure the Allstarlink DNS update service
In case a connection to the AllStarlink network is not desired:
enable = no
Timings :
The different settings of the RX/TX sequencing timings and delays are a bit complicated to understand because of their names.
The time diagram below helps to understand them better.
In rpt.conf
[wait-times]
telemwait = 2000 ; Time to wait before sending most telemetry
idwait = 1000 Time to wait before starting ID)
unkeywait = 1000 ; Time to wait after unkey before sending CT's and link telemetry
calltermwait = 2000 ; Time to wait before announcing "call terminated" [8] (or your node number)
hangtime = 500 ; squelch tail hang time (in ms) (optional, default 5 seconds, 5000 ms)
althangtime = 0 ; longer squelch tail
totime = 60000 ; transmit time-out time (in ms) (optional, default 3 minutes 180000 ms)
The following is a synopsis of the operation of the LF stages in the CM109 with the assigned audio parameters
Good calibration of the audio levels is essential to ensure good retransmission quality and a constant level from node to node.
If the URI interface card has its own transmit and receive level settings (pots), start with mid-range settings.
The difficulty is to keep an acceptable audio level for the DSP chip input.
Pre-emphasis and de-emphasis must take place somewhere, and only once!
They take place either in the transmitter (pre-emphasis), the receiver (de-emphasis), or in the interface board via the Asterisk DSP.
It's best to use the Asterisk DSP to ensure the same audio bandwidth on all nodes. This requires that the receiver and transmitter used have an unprocessed output and input, also known as a "discriminator", "direct", "flat", etc...
In addition, DSP operation of CTCSS decoding and squelch often are better than those of the receivers.
If the receiver has no discriminator output, use mode rxmode = "speaker". If the transmitter has no direct input, use mode txprelim = yes.
Note 1 : In the following procedures, if the test bench allows a choice between different bandpass or lowpass filters for audio detection, use the 0.3-3 kHz bandpass filter. The additional deviation introduced by the CTCSS should not be taken into account. (to be checked)
It will then not be necessary to disable/enable CTCSS generation in the following procedures.
CTCSS deviation is measured using the test bench's 300 Hz low-pass filter.
Some test benches don't have all these options, so you'll need to take that into account when making your settings.
Setting the transmitter audio level
Checking the maximum deviation of the transmitter
1) Disable CTCSS generation in the transmitter. (If CTCSS is not used or see note 1, this step and steps 6 and 7 are not necessary)
2) Connect the AF generator to the TX audio input being used (microphone or other depending on model). Set the level as low as possible and the frequency to 1 kHz sinusoidal. Connect the TX antenna output to the test bench and switch to transmit.
3) Check the deviation, and increase the AF level gradually until the deviation does not increase. This is the maximum possible deviation through the TX.
If the input is direct to the modulator, then the maximum deviation can be very high.
4) If the deviation is greater than 5 kHz, adjust the adjustment potentiometer or the software value for maximum deviation of the transmitter to 5 kHz. Some distortion is likely to occur as the TX limiter has kicked in.
5) Reduce the level of the AF generator to achieve a deflection of 3 kHz, there should be no distortion. Note the value of the AF generator voltage.
6) If necessary, reactivate the CTCSS generation in the transmitter.
7) If the deviation value has changed (see note 1 above), it should not exceed 3.6 kHz. If so, adjust the CTCSS level on the TX to this maximum value of 3.6 kHz.
With a transmitter that has a pre-emphased modulation input. ( mode txprelim=0 )
Set the value of txmixaset or txmixbset = 500 (usbradio_tune_usb.conf file) to start. Increase or decrease it later if necessary.
txmixa = voice ou composite
txmixb = no
txprelim = no
txlimonly = no
txtoctime = no ; ou autre suivant convenance
1) Disable CTCSS generation in the transmitter. (see note 1 above)
2) Check if the command "Test tone on/off cop,4", normally *904 in rpt.conf is enabled. If not, validate it and restart Asterisk.
3) Switch to Asterisk CLI mode, online command mode. (asterisk -r)
4) From the CLI, type rpt fun node *904 (node = number of the node to test)
5) The transmitter should go into transmit mode and transmit a 1 kHz tone. Adjust the URI potentiometer to obtain a deviation of 3 kHz, or change the txmixaset (or txmixbset) value using radio tune txvoice xxx (0-999)
6) Disconnect the transmission with the command rpt fun nr_du_node #.
7) If the CTCSS has been switched off, switch it on again and repeat the 3 previous steps. The deviation should not exceed 3.6 kHz.
If not, adjust the CTCSS generation level for a maximum deviation of 3.6 kHz using the internal TX setting if TCS is generated in the TX.
8) If the TCS is generated by the sound card: radio tune txtone xxx to obtain a CTCSS deviation of 600 Hz
If the level is not sufficient or too high, change the txmixaset value and repeat the procedure.
With a transmitter without pre-emphasis (flat mode txprelim = 1)
Set txmixaset = 500 (usbradio_tune_usb.conf file) to start with. Increase or decrease it later if necessary.
txmixa = composite
txmixb = no
txctcssdefault = 88.5
txprelim = yes
txlimonly = no
txtoctime = no
1) Check if the command "Test tone on/off cop,4" (normally *904) in rpt.conf is enabled. If not, validate it and restart Asterisk.
2) Switch to Asterisk CLI mode, online command mode. (asterisk -r)
3) Enter radio tune txtone 0, to stop TCS generation.
4) From the CLI, enter rpt fun node *904 (node = number of the node to test) or use the DTMF command *904
5) The transmitter should go on transmit and transmit a 1 kHz tone. Adjust the URI potentiometer to obtain a deviation of 3 kHz, or change the txmixaset (or txmixbset) value using radio tune txvoice xxx (0-999)
6) Cut the transmission with the command rpt fun nr_du_node #.
7) Enter radio tune txtone xx, set the xx value for a deviation of 600 Hz. The transmission takes only a few seconds. Pay attention to the measurement with the bench (note 1)
8) Enter rpt fun nr_du_node *904, to transmit the 1 kHz AND the TCS simultaneously
7) The deviation must not exceed 3.6 kHz (1000 Hz measurement + TCS). Pay attention to note 1!
If not, adjust the CTCSS generation level for a maximum deviation of 3.6 kHz.
If the level is not sufficient or too high, change the txmixaset value and repeat the procedure.
Note: It seems that if the txmixaset + txctssadj value > 1000, distortion may occur. You should therefore use the 2 audio outputs of the DSP and dedicate the left channel (txmixaset) for the voice and the right channel (txmixbset) for the TCS.
Adjusting the receiver audio level
The MICIN input of the sound card chip is connected to the receiver. The voltage must be high enough to allow correct decoding but not too high to saturate the DSP input. (500 mV for example)
Start by setting the parameter rxboost = 0 to insert the 20 dB attenuator (the CM109 doc. talks about an amp that doesn't actually exist)
The amp that injects the signal into the ADC is set by the rxmixerset parameter, (usbradio_tune_usb.conf file). Start with a value of 250 (from 0-999).
If the settings do not give good results, change this value.
For a receiver with de-emphasis (output on speaker or LF preamp) :
rxdemod = speaker
rxctcssoverride =1 (squelch par détection de porteuse issu du récepteur)
carrierfrom = usb ; ou usbinvert (signal squelch vient de la carte interface USB)
ctcssfrom = no (pas de détection du CTCSS par DSP)
1) Inject a signal of several microVolts modulated at 1 kHz with a 3 kHz excursion into the receiver.
2) In CLI mode, type radio tune rxvoice, the software will adapt the LF level after several measurements.
3) Type radio tune save to save the settings which will be read at each start-up. (usbradio_tune.conf file)
4) Turn off the generator, to avoid a bug when rebooting Asterisk.
5) Reboot Asterisk by typing rpt restart, and check if the transmitter excursion follows linearly the receiver one. ( 1kHz -> 1kHz, 2 kHz -> 2 kHz, etc...)
For a receiver with a non-de-emphasis output (FM discriminator output):
rxdemod = flat
carrierfrom = dsp (détection de porteuse vient du DSP de la carte interface USB)
ctcssfrom = dsp (détection CTCSS vient du DSP de la carte interface USB)
1) The receiver should have no squelch and therefore generate permanent noise without signal.
2) In Asterisk CLI mode, type radio tune rxnoise, and the software will take several measurements and calculate an average value.
3) Inject into the receiver a several microVolts signal modulated only with a 1 kHz audio with a 3 kHz deviation (without CTCSS).
4) In CLI mode, type radio tune rxvoice , the software will adapt the AF level after several measurements.
5) Switch off modulation at 1 kHz, and modulate with the desired TCS tone (88.5 Hz) with 600 Hz deviation.
6) Type radio tune rxtone for automatic setting of CTCSS decoding.
7) Switch off generator.
8) Squelch adjustment: entering radio tune rxsquelch will give the measured value of the squelch threshold. Note this value. The level of the rxsquelch parameter must be set approximately 50-100 higher than the measured value for correct operation. Type radio tune rxsquelch <value> (between 0 and 999)
9) Type radio tune save to save the settings, which will be read at each startup. (usbradio_tune.conf file)
10) Switch off the generator, to avoid a bug at Asterisk reboot.
11) Reboot Asterisk by typing rpt restart, and check that the transmitter's deviationlinearly follows that of the receiver. ( 1kHz in-> 1kHz out, 2 kHz -> 2 kHz, etc...)
By default, ASL comes with English sound files.
They are in /var/lib/asterisk/sounds
To change the language and use French sound files for example, you need to create a tree structure identical to the one found in the sounds directory.
Namely:
fr/rpt
fr/digits
fr/letters; etc...
Then place the French sound files in the same directories as for the English version.
To activate the French version, modify the file /etc/asterisk/asterisk.conf
If the stanza [config] does not exist, create it.
Add the following line: languageprefix = yes
Modify the file /etc/asterisk/chan_dahdi.conf
In the stanza [channels], add the line: language = fr
Restart Asterisk.
ASL uses sound files for telemetry and beacon functions.
These files are mainly in ulaw format which is a standard used by Asterisk and is a US standard designed for telephony.
It is a format without data compression or RAW.
Be careful, some softwares or websites provide files in RAW-ULAW format, but with a RIFF header which generates a parasitic noise at the beginning of the reading by Asterisk. It is absolutely necessary to obtain ulaw files without headers.
You can use the free software Audacity which allows you to record a sound file, manipulate it and save it in the right format.
You can either record the file with a microphone or use an online TTS (Text to Sound) generator.
Most of these generators require a subscription to save the created sound file. But there is a way around this by recording the browser's demo sound using Audacity.
Once the sound file is obtained, it must be switched to mono if it was recorded in stereo:
- Track" menu
- Sub-menu "Mix".
- Choice "Stereo to mono mix".
So that all the sound files have the same volume, the level must be normalised:
- Effects" menu
- Volume and compression" submenu
- Choice "Amplitude normalisation".
You must then choose a method and a level of normalisation. Here LUFS at -16 dB.
The only thing left to do is to save the file in the correct format, i.e. ulaw :
- Export" menu
- Sub-menu "Export to WAV".
- Choose the right formats as below:
APRS configuration, file gps.conf
This file is used to set up the APRS tag if you want to send the coordinates of a relay on the APRS network.
Below is an example for one of our sites:
call = TK1ZAR ; callsign (including SSID) for APRS purposes password = 12345 ; Password for APRS-IS server for above callsign comment = Sud UHF (430.175, +9,4, TCS 88.5) http://tknet.radioamateur.tk ; Text to be displayed associated with this station server = xxxxx.net ; APRS-IS server to report information to port = 14580 ; port on server to send data interval = 600 ; Beacon interval in seconds icon = r ; A CAR (default) Icon do be displayed for station on APRS display (see below) ;comport = /dev/ttyS0 ; Serial port for GPS receiver (specify this only if using GPS receiver) ;baudrate = 4800 ; Baud rate for GPS receiver (specify this only if using GPS receiver) ;debug = y ; set this for debug output freq= 430.175 ; Display Frequency of station tone=88.5 ; CTCSS tone of station (0.0 for none) lat=41.653192 ; Fixed (default) latitude in decimal degrees lon=9.178372 ; Fixed (default) longitude in decimal degrees elev=1068 ; Elevation of Antenna in Meters (*NOT* HAAT) power=3 ; Power level (see below) height=8 ; Antenna Height in HAAT (see below) gain=3 ; Antenna Gain (see below) dir=0 ; Antenna Direction (see below)
If no GPS receiver is connected to the controller, the comport and baudrate lines MUST be commented. Enter the lat and lon values.
The values power, height, gain, dir are coded on a single digit from 0 to 9. This results in an important approximation.
If power = 0, only the comment information will be transmitted. This is useful if you do not want to broadcast the other information.
The HAAT value is NOT the altitude of the antenna above sea level, but the effective height of the transmitting antenna, which is the height of the antenna above the average height of the terrain between the distances of 3 and 15 km in the direction of the receiving antenna!
The following site allows you to calculate the HAAT of a site: https://www.itu.int/SRTM3/index-fr.html
WARNING, latitude and longitude values must be entered as 6-digit decimal values without commas or full stops!
In general, unless the repeater is located on a peak which is the highest in the region, the HAAT value is lower than the altitude above sea level.
Once the HAAT value is obtained, it must be converted to feet (feet = m x 3.281).
The data values for power, height, gain, dir can be converted using the table below, or they can be calculated:
power = the square root of your power
height = ln(HAAT/10) (ln = log neperian)
In both cases, choose the closest value.
DIGITS 0 1 2 3 4 5 6 7 8 9 ------------------------------------------------------------------- POWER 0, 1, 4, 9, 16, 25, 36, 49, 64, 81 watts SQR(P) HEIGHT 10,20,40, 80,160,320,640,1280,2560,5120 feet LOG2(H/10) GAIN 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 dB DIR omni,45,90,135,180,225,270, 315, 360, . deg (D/45)
Beacon broadcast with a crontab
You may want or need to broadcast a "beacon" using a sound file to a local node or to all nodes at regular intervals or at a specified time.
In crontab :
# Example of job definition:
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# | | | | |
# * * * * * user command to be executed
For a broadcast on all nodes :
00 * * * * sudo /usr/sbin/asterisk -rx “rpt playback node# /sound_file"
For a broadcast on one node only :
00 * * * * sudo /usr/sbin/asterisk -rx “rpt localplay node# /sound_file"