GW Signal

[Oidaray]

Although the signals are now defunct, I would like to introduce myself as the creator of the GW-PSK-2,4,8 and GW-OFDM signals while I was employed by Globe Wireless. From what I understand GW was not very protective of the MODEM specifications (there is no IP). They are basically a service provider and not a radio manufacturer. If anyone is still interested, I can answer questions or "grade" a decoder.

I hope decoding pf the signals was not too much trouble.

 

[ka3jjz]

Welcome aboard,. Oidaray. Yes there are one or two decoding packages that can handle the Globe Wireless PSK stuff - I believe Sorcerer and Rivet both can, and likely some of the expensive decoders like Krypto500, Hoka, Wavecom and 1 or 2 more that escape my mind at the moment.

They are still heard on occasion; you can find reports of them in the UDXF Yahoo group. Hardly defunct.

Any insight you can give - that doesn't violate your confidentiality rules (no doubt there are some you are still under legal rights for) is certainly welcome. Mike

 

[Oidaray]

initial engineering

Thanks for allowing me into the forum. My expertise is in wireless communications and digital signal processing(DSP). I hope I can contribute.

A little background:

At GW they provided an audio and PTT interface kit between a custom DSP modem and a SSB transceiver. So, they did not make the radio but only the modem and interface. A computer was used to control and to send/receive email.

The legacy GW signals were FSK. The hardware was updated to use a better DSP processor. This required the porting of DSP code to the new processor.

There was the need to increase the signal bandwidth and corresponding data rate. Originally, the channel bandwidth was 500Hz. In addition to FSK, PSK-2,4,8 modes were added with an adaptive multi-rate (AMR) capability ( I think some decoders detected this AMR). The PSK, of course, is more bandwidth efficient allowing for increased data rates over FSK.

An OFDM signal was created to use the full audio band(~3KHz) with the same 1700 Hz center frequency. This resulting in the need to update the hardware again.