Still no usable 8.33 kHz steps in SDR#?

Edelweiss

Author of: Scanning the UK Airbands with the Beast
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Just reactivated my airspy on VHF using a newer version of SDR#. @Chesterdrawers mentioned in a short 2017 thread about this and I noticed that it is still not working or I am doing it wrong. Turn on 8.33 + "snap" on top and it appears to roughly add 8 1/3 but gets confused, the reference offset is also wrong i.e. you can't ever tune a round frequency say 125.000.
Tuning by manual entry 125.000 then one step up makes 125.011666 (???), then on step back it goes to 125.003333
125.003333
125.011666
125.019999
125.028332
etc.

Come one, that is not usable. I mean if one has programming skills to write something like SDR# or the cool plugins I can't believe it is such an unachievable challenge to add 8+1/3 kHz in the required manner. Can that not please be fixed? Kind of useful in Europe at least. SDR Console also seems to have trouble with that. Could it be an issue with the radio that doesn't not like the steps? I'm sure this can be fixed. Oddly HW scanners seem to handle it :)
Just wondering


M
 

morfis

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Back in 2015 there was a plugin to correctly implement it. Also correctly implemented in the scanner plugin presumably or else there would be a whole load of anoraks frothing at the mouth instead of proclaiming how wonderful it is to scan the whole of airband in 0.1 jiffys
If it's not done properly by sdrsharp itself then that probably means anoraks are on the very long list of people Youssef holds in contempt.
 

merlin

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8.33 KHz is the maximum bandwidth per channel.
Looks like you are trying to use this as a channel step and that won't work. Channels are 25 KHz separation.
There was a notion of narrowbanding with 8.33KHz separation giving near tripple the number of channels.
At least in north America, this has not been implemented as yet. A quick cut/paste:

Increasing air traffic congestion has led to further subdivision into narrow-band 8.33 kHz channels in the ICAO European region; since 2007, all aircraft flying above FL195 are required to have communication equipment for this channel spacing.[2][10][11][12] Outside of Europe, 8.33 kHz channels are permitted in many countries but not widely used as of 2012.

As for SDR#, I just tried this and have no problems. Maybe go back to your original version.
 

KevinC

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8.33 KHz is the maximum bandwidth per channel.
Looks like you are trying to use this as a channel step and that won't work. Channels are 25 KHz separation.
There was a notion of narrowbanding with 8.33KHz separation giving near tripple the number of channels.
At least in north America, this has not been implemented as yet. A quick cut/paste:

Increasing air traffic congestion has led to further subdivision into narrow-band 8.33 kHz channels in the ICAO European region; since 2007, all aircraft flying above FL195 are required to have communication equipment for this channel spacing.[2][10][11][12] Outside of Europe, 8.33 kHz channels are permitted in many countries but not widely used as of 2012.

As for SDR#, I just tried this and have no problems. Maybe go back to your original version.
The OP is in Europe where 8.33 spacing was implemented years ago.
 

Edelweiss

Author of: Scanning the UK Airbands with the Beast
Joined
Jun 8, 2019
Messages
137
Location
England
8.33 KHz is the maximum bandwidth per channel.
Looks like you are trying to use this as a channel step and that won't work. Channels are 25 KHz separation.
There was a notion of narrowbanding with 8.33KHz separation giving near tripple the number of channels.
At least in north America, this has not been implemented as yet. A quick cut/paste:

Increasing air traffic congestion has led to further subdivision into narrow-band 8.33 kHz channels in the ICAO European region; since 2007, all aircraft flying above FL195 are required to have communication equipment for this channel spacing.[2][10][11][12] Outside of Europe, 8.33 kHz channels are permitted in many countries but not widely used as of 2012.

As for SDR#, I just tried this and have no problems. Maybe go back to your original version.
Which version are you using? 8.33 kHz is in common use in Europe. While I can tune any frequency I like directly I cannot correctly step in 8 1/3 steps as I can do with 1, 5 kHz etc. it seems to be the fraction that is preventing the proper increments.
Manually tune to say 125 MHz. Then set steps to 8.333 kHz, click Snap. Then click on the Up triangle next to the frequency and tell me what you get. I get 125.011666. The next step up from there is +8.333 i.e. 125.019999. So the snap grid offset seems to be a problem for a start.
If you do not click snap it sort of works but will never hit the "round " frequencies .000, 0025, 0.050, 0.075 e.g. it adds some decimal fraction as to e.g. land close but next to the desired frequency e.g. the third step is already 125.02499 instead if 125.0250 so that eventually 125.149994 is 125.150. Of course good enough for use but unreadable. And it will not snap to the grid when you click into the spectrum.
 

merlin

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Well, I don't click snap. With 8.33 KHz step, that is what I get. This is with SDR# Studio 1.0.0.1919 Airspy.
My step sizes go from 1 Hz to 1 MHz (Ibeam setting) IE:
I use the keyboard up/down quite a bit. but consider, I barely get my local ATIS and maybe catch air to ground once or twice a month, so not much airband work.
 

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merlin

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Update. OK, if I skate down a dozen or more channels, I do get a little frquency skewing. If I correct the frequency and go back up,
the skewing is back.
It may be that the step in SDR# is 8.330000 and the actual step is 8.333333.....
 

G7RUX

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Jul 14, 2021
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8.33kHz channels do indeed cause a lot of confusion, especially around how they are specified over the air and on the radios. For example Tower telling you “129.400“ means a frequency of 129.400 MHz with a channel step/width of 25 kHz. Tower telling you “129.405” means the same frequency but in 8.33 kHz step/width! It gets even more confusing when it’s not a nice round number!

Back to the original post point, I also see problematic behaviour with the Malahit DSP2 in that selecting a step of 8.33 kHz leads to the frequency raster being offset; I cannot tune to 129.400 MHz as the radio chooses 129.398220 or 129.406550.
 
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