OT inquiring about information on satellite modems
 

I bought a Comstream CM 701 Modem thru eBay. It has an input card but I
cant find information on what frequency the card is designed to accept.
The IF input card is marked 5MB Modem.
If there is anyone reading this and is willing to point me to where I can
find information on the Comstream horizontal card (plig-in), I'd sure
appreciate knowing where I can find it.

Jerry KD6JDJ

OT inquiring about information on satellite modems
 

On Sun, 01 Mar 2009 06:06:13 +0000, Jerry wrote:

I bought a Comstream CM 701 Modem thru eBay. It has an input card but
I cant find information on what frequency the card is designed to
accept. The IF input card is marked 5MB Modem.
If there is anyone reading this and is willing to point me to where I
can
find information on the Comstream horizontal card (plig-in), I'd sure
appreciate knowing where I can find it.

Jerry KD6JDJ

Look he

http://www.1megastar.com/cm701man.pdf



--
73's
Ken Slimmer, WA0SBU

OT inquiring about information on satellite modems
 

"Ken Slimmer" wrote in message
...
On Sun, 01 Mar 2009 06:06:13 +0000, Jerry wrote:

I bought a Comstream CM 701 Modem thru eBay. It has an input card but
I cant find information on what frequency the card is designed to
accept. The IF input card is marked 5MB Modem.
If there is anyone reading this and is willing to point me to where I
can
find information on the Comstream horizontal card (plig-in), I'd sure
appreciate knowing where I can find it.

Jerry KD6JDJ

Look he

http://www.1megastar.com/cm701man.pdf



--
73's
Ken Slimmer, WA0SBU

Hi Ken

Thanks for the reference. I read it (again). Actually, I scanned it.
The information in that manual is difficult for me to understand. Still, I
gain a little more understanding about this"BPSK" system each time I reread
the documents.
My original goal was to assemble an antenna with the needed amplifiers and
demodulators so I can see NOAA's Earth images on the computer monitor.
When I began this project I thought the demodulator would be easy to 'hook
up'. That was a big mistake. The BPSK demodulation is like a seperate
science.

It appears that I need to find a proper card for this CM 701. I find no
reference to the "5MB Modem card in the CM701 I now have.

Jerry KD6JDJ

OT inquiring about information on satellite modems
 

On Sun, 01 Mar 2009 23:48:34 +0000, Jerry wrote:


Hi Ken

Thanks for the reference. I read it (again). Actually, I scanned
it.
The information in that manual is difficult for me to understand.
Still, I gain a little more understanding about this"BPSK" system each
time I reread the documents.
My original goal was to assemble an antenna with the needed amplifiers
and
demodulators so I can see NOAA's Earth images on the computer monitor.
When I began this project I thought the demodulator would be easy to
'hook up'. That was a big mistake. The BPSK demodulation is like a
seperate science.

It appears that I need to find a proper card for this CM 701. I find
no
reference to the "5MB Modem card in the CM701 I now have.

Jerry KD6JDJ



Jerry;
Sounds like a fun project, too bad I don't have one to play with.

The Comstream CM701 modem normally uses a Comstream proprietary encoding mode and uses BPSK or QPSK to stream data. The IF is 70 MHz which is rarely used anymore. About the only thing that will decode the stream is an ABR200/202 receiver. I am afraid for the purposes you are desiring, the CM701 is going to be of little value. I have worked with them for years on SCPC program distribution networks for radio stations.

NOAA downlinks are on a variety of frequencies, but mostly on 137 MHz or 1681 MHz (or thereabouts).

Sorry,
Michael