Radio Modems: Difference between revisions

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== Overview ==
[http://www.pacificcrest.com Pacific Crest] makes radio modems, principally for connecting a GPS rover with a fixed reference station to allow submeter accuracy.
[http://www.pacificcrest.com Pacific Crest] makes radio modems, principally for connecting a GPS rover with a fixed reference station to allow submeter accuracy.


I have 3 RDDR-96 "Blue Bricks". I got them at a garage sale along with a [[Magnavox GPS reference station]] Also included were two omni directional antennas, a YAGI directional and a 35 watt linear amp.
I have 3 RDDR-96 "Blue Bricks". I got them at a garage sale along with a [[Magnavox GPS reference station]] Also included were some rubber ducky omni directional antennas, a Larsen base station antenna, a Larsen YAGI directional and a [[TPL Communications PA6-1AC amplifier]].


The Blue Bricks can operate in two modes, transparent and packet. In transparent mode a pair of the radios acts as a replacement for a serial cable operating at 9600 bps. In packet mode, one radio can be the source of a data stream and several can be receivers, allowing in my case one base station and two rovers.
The Blue Bricks can operate in two modes, transparent and packet. In transparent mode a pair of the radios acts as a replacement for a serial cable operating at 9600 bps. In packet mode, one radio can be the source of a data stream and several can be receivers, allowing for example in my case one base station and two rovers.


So far I have powered them up individually with their rubber ducky antennas attached and confirmed they transmit by tuning my Kenwood TH-6A handheld to their frequency and listening the bleeps when I type.
So far I have powered them up individually with their rubber ducky antennas attached and confirmed they transmit by tuning my Kenwood TH-6A handheld to their frequency and listening the bleeps when I type.


My radios came from the factory tuned to 420 Mhz. This means that I can operate them using my amateur radio operator's technician license. It's in the 70cm band.
My radios came from the factory tuned to 420 Mhz. This means that I can operate them using my amateur radio operator's technician license. It's in the 70cm band. (See http://www.arrl.org/FandES/field/regulations/bandplan.html#70cm)
(See http://www.arrl.org/FandES/field/regulations/bandplan.html#70cm)


The typical use for these radios is to connect
== My applications ==


Current plan is to string a cable to the roof for the YAGI, and send out DGPS corrections from the reference station.
I have a couple ideas for things I want to try with this set up.
 
=== DGPS ===
 
Send out DGPS corrections from the GPS reference station.


The rover will be a Leica 9400 or a Garmin or possibly a Trimble. Probably all three but not at the same time.
The rover will be a Leica 9400 or a Garmin or possibly a Trimble. Probably all three but not at the same time.
=== Garmin Fleet Management ===
Connect to a server running software compatible with Garmin's Fleet Management protocol. Put a radio modem in a car that has a Garmin PND in it and see what we can do.
== Antenna set up ==
I am not sure what part of town I will be in, so I am trying the omni antenna first.
Larsen BSA Kit = "Base station antenna"
Cut radials - for frequencies above 400 MHz they should be 7 inches.
My main element is a PO series. For 420 Mhz, the lower portion should be 10 inches.

Latest revision as of 01:52, 28 February 2010

Overview

Pacific Crest makes radio modems, principally for connecting a GPS rover with a fixed reference station to allow submeter accuracy.

I have 3 RDDR-96 "Blue Bricks". I got them at a garage sale along with a Magnavox GPS reference station Also included were some rubber ducky omni directional antennas, a Larsen base station antenna, a Larsen YAGI directional and a TPL Communications PA6-1AC amplifier.

The Blue Bricks can operate in two modes, transparent and packet. In transparent mode a pair of the radios acts as a replacement for a serial cable operating at 9600 bps. In packet mode, one radio can be the source of a data stream and several can be receivers, allowing for example in my case one base station and two rovers.

So far I have powered them up individually with their rubber ducky antennas attached and confirmed they transmit by tuning my Kenwood TH-6A handheld to their frequency and listening the bleeps when I type.

My radios came from the factory tuned to 420 Mhz. This means that I can operate them using my amateur radio operator's technician license. It's in the 70cm band. (See http://www.arrl.org/FandES/field/regulations/bandplan.html#70cm)

My applications

I have a couple ideas for things I want to try with this set up.

DGPS

Send out DGPS corrections from the GPS reference station.

The rover will be a Leica 9400 or a Garmin or possibly a Trimble. Probably all three but not at the same time.

Garmin Fleet Management

Connect to a server running software compatible with Garmin's Fleet Management protocol. Put a radio modem in a car that has a Garmin PND in it and see what we can do.

Antenna set up

I am not sure what part of town I will be in, so I am trying the omni antenna first.

Larsen BSA Kit = "Base station antenna"

Cut radials - for frequencies above 400 MHz they should be 7 inches.

My main element is a PO series. For 420 Mhz, the lower portion should be 10 inches.