Radio pass band

[Ron Patton]

Hi Folks,

I'm just curious to know if narrowing the receive pass band of a transceiver may help with the decoding abilities of FreeDV when in RADE mode?  The documented bandwidth of RADE is 1500Hz.  When the signal is centered at 1500Hz,  the signal is from 750Hz to 2250Hz.   If it were to set my low cut filter to say 500Hz and the high cut filter to 2700Hz, would that aid/assist the decoding capabilities of RADE?  Just curious.

73,

Ron / W4MMP

[Mooneer Salem]

Hi Ron,

I haven't tried this yet but definitely give this a shot and let us know how it goes :)

Thanks,

-Mooneer K6AQ

--
You received this message because you are subscribed to the Google Groups "digitalvoice" group.
To unsubscribe from this group and stop receiving emails from it, send an email to digitalvoice...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/digitalvoice/64228967-8614-46e7-bcd6-b75f88893075n%40googlegroups.com.

[Rick, W7IMM]

Ron,

I use an IC705 for FreeDV and I have always used minimum (for the mode)  bandwidth for receive and I always set the transmit bandwidth at 500-2500Hz (which is the narrowest tx  bandwidth selectable in the SSB-D mode)

Using the narrowest bandwidth for receive seems to reduce adjacent channel interference

73/Rick

[Stefan N.]

These are my experiences:

I use the settings mentioned by Ron (750 Hz to 2250 Hz) with my Flex in TX and RX. In RX mode, it helps cut interference from the sides because of the narrow bandwidth. Further reducing the bandwidth would work, but it would reduce the audio quality. 

TX: This produces a narrow, sharp, and clean 1500 Hz TX signal that wouldn't disturb others with the wider signal from the FreeDV software in RADE mode.

I'm not sure, but I have a feeling that setting 1500 Hz TX BW is also more efficient.
Since these settings are not possible with any radio, it would be nice to have the option to reduce the TX BW in a future version of the software, if it's not already planned.

Thanks to the developers for their outstanding work.

73, Stefan - DF6VI

[Michael Carey]

Hi Ron,

I have done this with my HPSDR/PowerSDR transceiver. 

My RADE transmit filter is set at 700/2250 and the receive filter is 560/2375. I've not done any scientific tests but my real world experience is that FreeDV in RADE mode does appear to decode weaker signals better with the narrower filter.

The narrow transmit filter cleans up the "grass" on each side of the main transmit signal :-)

73

Michael.
VK5LN/VK5ZEA