DFM,FM observations when used to copy satelitte downlinks

W0DHB

This past week at least 2 Satellites were launched that have PSK31 transponders that uplink on 10m and downlink on 70cm.
The downlink is FM, the uplink is DIGU.

PSK31 Beacons are transmitted centered at 312Hz.

Currently both FM and DFM audio appear to cut off at about 300Hz and this prevents the beacon from decoding correctly.

Is there any user setting to change this cut off to a lower frequency, say 150Hz which is the what the PowerSDR cutoff ? 

K6OZY

+Me Too on this thread.   Please make that adjustment.

Tim - W4TME

There is no user configuration to change this cutoff.  It is done this way to prevent CTCSS tone bleed thru.

W0DHB

CTCSS bleed through isn't a issue with DFM though, correct ?
Have it adjust itself based on the tone frequency you're using ?

K6OZY

I've always thought that that should be a user option.   This is a good example of a use case where we don't need it.   I also don't want it for when I am talking simplex to friends.

Tim - W4TME

I have entered this report into our bug tracker for further investigation.  Please report any additional information related to this specific issue in this community topic.

Jim W3IPO

Just to add another Me Too

W0DHB

An update to my original post: The upcoming FOX satellites are going to be using sub audio telemetry so that telemetry can be carried on the FM downlink along with voice. Testing with some AMSAT test files shows that SmartSDR with it's 300Hz brickwall does not allow the telemetry through. The 5000 which has a gradual roll-off below 150Hz allows the telemetry through marginally. Pretty please, can we get a user option in SmartSDR?! Thanks Dave W0DHB

K6OZY

This was addressed in 1.5.   I was involved in the FM tweaks.

#2112 FM post-demod default filter width to 200-4500 Hz
#2087 FM: Post demod filters in DFM are now 0-5500 Hz to allow digital SAT operation
#2087 FM: Transmit filters can now be changed

W0DHB

Thanks for pointing that out, next time I'll rtfm :-) My apologies .

glider73

Running the latest version of SSDR on a 6600M I have found what appears to me a DFM filter issue which can be seen when using the UZ7HO high speed sound modem software monitoring the open squelch audio stream. If I preselect any filter width and go to DFM the filter opens to about 5400 Hz if I select any other DFM filter width the filter closes to about 2700 Hz and can't be opened up without going into FM mode and then back to DFM. Also why does the DFM filter selection have eight options but really there is only one selection available?

glider73

The filter window size changes in SSDR but not in the actual audio stream which made me think it was working but checking the audio stream it appears to not actually widen to match the filter size chosen.

Mike-VA3MW

When you are testing this, I assume you are using the DAX Audio stream and not the Audio from the back of the radio?

glider73

Using DAX only I sent in a ticket today with some documentation they sent in on to engineering. I have not tried sat transmissions yet with the Flex I have other hardware was taught if you can't hear em you can't work em it does work great for reception was getting ready for 9600 baud see if it can catch up with my IC-910H hi hi. 73 N3ICK

W0DHB

There is an outstanding bug report about this (#4688) that I reported several years ago that covers this issue.

Because of the relatively few people using 9.6K packet it has not been prioritized.

Please update your ticket to reference #4688 as it may help getting some resource applied to it.

Thanks

Dave W0DHB