RTCM Voting Configuration

Voting nos permite tener un repetidor con un transmisor de alta potencia a la ves y contar con dos o más receptores periféricos.

Hardware needed

Main Site

The Main Site must be conformed by al least the following hardware:

• 01 Duplexer and antenna or double antenna set (Tx/Rx).
• 01 Motorola Pro3100, Pro5100, Pro7100 or MTR2000(Rx).
• 01 Motorola Pro3100, Pro5100, Pro7100 or MTR2000(Tx).
• 01 Duplexer or double antenna set.
• 01 Micro-Node RTCM board.
• 01 Garmin GPS model GPS18x LVC, 5m.
• 01 Raspberry Pi model 2A, 3A or 3B.
• 01 Wired Internet connection with port forwarding capabilities.

Peer Sites

Each Peer Site must be conformed by al least the following hardware:

• 01 Antenna (Rx).
• 01 Motorola Pro3100, Pro5100, Pro7100 or MTR2000(Rx).
• 01 Micro-Node RTCM board.
• 01 Garmin GPS model GPS18x LVC, 5m.
• 01 Wired Internet connection with port forwarding capabilities.

Tuning Hardware

• Service monitor.

Configuration

Edit the voter.conf where 12345 should be your node number and each Site# will define your Main Site or each Peer Site. pass# is the individual password for each site. It is important to notice that each site must have a different password.

[general]
port = 667
buflen = 500
password = BLAH
utos = y

[12345]
MainSite0 = pass0,transmit,master
PeerSite1 = pass1,transmit
PeerSite2 = pass2,transmit
PeerSite3 = pass3,transmit
PeerSite4 = pass4,transmit

# plfilter = n
; txctcss = 100.0
; txctcsslevel = 100
; txtoctype = none

thresholds = 255,110=5
; linger=6
; streams = 12.34.56.78:1667

RTCM

Log in using telnet, the default user is admin and the default password is radios.

Firmware update

The VOTER/RTCM firmware is updated with a Windows program EBLEX C3 Programmer. Download from here. Put both the exe and the ini file in a folder.

If you are upgrading an RTCM be sure to use a .cry file that contains smt in the filename.

If you are upgrading a through-hole VOTER, do not use the smt files.

Save the .cry file in the folder with the .exe and .ini files.

Download the firmware here that is appropriate for your application.

Run the EBLEX Programmer:

• Fill in the target bootloader IP address (or the public IP, if your RTCM is behind a firewall) of the device.
• Click File and load the .cry file you are going to program.
• Click the Capture Target button.
• Reboot the VOTER/RTCM with TELNET (r option), power cycle, or use the reset button. In a moment you should see text come up on the programmer that it captured the target.
• Click the Program button.
• In a few minutes you will see some more messages including a program complete message.
• Click the Reset LIA button. The VOTER/RTCM will restart with the new firmware.

• TELNET into your VOTER/RTCM and verify the new version is loaded with menu 98:

GPS

The GPS should be connected thru the DB-15 port on the RTCM.

RTCM GPS pinout
RTCM	Direction	Garmin 18x LVC
6 GRX	<-- Rx Data	Green
7 GPPS	<-- Pulse Output	Yellow
8 GND	Ground	Black (2 cables)
13 +5V	V in	Red
14 GTX	--> Tx Data	White

Tuning

Don't disable COR in the RTCM/VOTER... it will cause it to disable the squelch and it will report an RSSI of 255 (full quieting) for all received signals.

RTCM Settings
Option	Parameter	Value
7	Tx Buffer Length	4000
8	GPS Data Protocol	0=NMEA
9	GPS Serial Polarity	0=Non-Inverted
10	GPS PPS Polarity	0=Non-Inverted
11	GPS Baud Rate	4800
11	External CTCSS	1=Non-Inverted
12	External CTCSS	1=Non-Inverted
13	COR Type	0=Normal

Level Settings

Setting the audio levels for the RTCM/VOTER is pretty straight forward. Just follow these steps:

• Step 1
  • Ensure you have a connection to your host Asterisk server/chan_voter instance
  • Send a 1kHz@3kHz on-channel, full-quieting signal in to the repeater's RX
  • Set the RX up so it reads 3kHz deviation on the RTCM's built in console meter

Now change the modulation from 1kHz tone to 800Hz followed by 1.8kHz and verify that the deviation level doesn't change as the tone frequency changes. Changing levels indicates a pre/de-emphasis issue.

If you are using the built-in "offline repeat" functions, fail the connection to the host Asterisk server, and make sure your repeat audio performs the same as above.

• Step 2
  • Now set the TX level pot to get 3kHz out of the transmitter (No PL)

Squelch Calibration

SW2-2 On to calibrate squelch. With the receiver connected and its antenna removed, switch on SW2-2. In the next few seconds the "Receive Signal Indicator" (LD3, Green) will flash On and off, then (hopefully) on steady. This indicates that the squelch calibration has occurred successfully. If unsuccessful, the LED will flash either fast to indicate that the discriminator noise level is too high, or slowly to indicate that the discriminator noise level is too low. Note, if SW2-3 is ON during this procedure, the "Diode Calibration" process will also occur.

SW2-3 On to perform "Diode Calibration". This may only be done in conjunction with a configuration parameter initialization (see SW2-1, above), or a "Squelch Calibration" (see SW2-2, above).

SW2-4 On to temporarily re-purpose LD4 and LD5 to allow for visual indication of RX input level (see "Rx Level Calibration", below).

Squelch Setting:

Once the "Squelch Calibration" procedure has been performed (see SW2-2, above), the squelch adjustment (R22) needs to be properly set. Make sure that the "External CTCSS" is set to "ignore" (value: 0). Adjust R22 until the Receive Signal Indicator (LD3) is lit. Then advance R22 clockwise until LD3 is no longer lit. That is the minimum squelch setting. You probably will want to crank it up at least another turn clockwise, because if you leave it there it will open on a REALLY low level signal. After proper setting has been achieved, return the "External CTCSS" configuration to its original setting.

Rx Input Level Calibration:

Place a full-quieting saturated signal on the receiver modulated by 1000 Hertz sine wave at 3KHz deviation. With SW2-4 ON, LD5 will indicate (by brightness) if the RX level is too low, and LD4 will indicate (by brightness) if the RX level is too high. So the idea is to tune R36 so that there is minimal brightness on both LD4 and LD5 (like a null, more or less). Alternatively, the "97" command from the console menu gives a more graphical method of setting the Rx input level.

RX/TX Buffers are NOT Both Millisecond Values

You might assume an RX buffer (in voter.conf) of 120ms would be equivalent of a TX buffer (in the RTCM) of 120ms. That is not the case.

The TX buffer is a number of 125 microsecond intervals, where the RX buffer is in milliseconds.

If you follow the buffer setting instructions, you should be fine, in most cases.

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RTCM Simulcasting

The RTCM/VOTER boards do support simulcasting, however, there are a bunch of quirks that one needs to be aware of.

9.6MHz Oscillator

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