Revised QO-100 DATV Bandplan - Please Read

[G8GKQ]

Following the extension of the released transponder bandwidth, and the revised beacon parameters, the BATC and AMSAT-DL have revised the bandplan for the transponder with some significant changes.

The full .pdf is here: https://wiki.batc.org.uk/images/9/92/QO ... n_V2.0.pdf

The Wiki page describing the changes is here: https://wiki.batc.org.uk/QO-100_WB_Bandplan

and this is how it looks:

Dave, G8GKQ

[AdrianH]

Hello Dave,

Just wondering if anyone has considered a numbering scheme, previously I found charts with 333KS4 333KS5 etc. Wonder if the number ranges should start from the top and work down in frequency to push home use of the narrow section prior to wide and narrow section?

As 500 333 and 250 are all going to use the same 333 slots any suggestions out there on what to name them. Also 125 and below
slots.
F5OEO uses the convention in his Pluto firmware there are charts in Minitioune. I imagine it will be a day or to before software catches up, but you never know?

Just thoughts.

Adrian

[g0mjw]

Hi Adrian

I mentioned this too but nobody seems interested.

We could have channels 1 to 27. This fits 125K and below channels across the band but we only normally use 18-27
For 333 the channels would be odd, i.e. 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25 and 27 but only normally use 13-27 with a preference for 19-27
The wideboys channels would be 3, 9 and 13

Now obviously that's far too difficult for the average ham to understand, hence I think the lack of interest.

Additionally I would have liked to see the top 500 kHz reserved for narrow band only i.e- 66ks and below. We could get 5 users in that channel. It's nominally identified for that use but the chances of that being respected when busy are extremely low.

Mike

[G8GKQ]

Hi Mike

The channels that I proposed in the original (2018-issue) bandplan were rarely referred to by their names, hence dropping them in this version. However, as you have noticed, all the channels are now on a more logical grid.

Could we come up with a solution where there was an "easy mental arithmetic" relationship between the channel number and the frequency - even if that meant some channel numbers were illegal? A bit like S20, S21 and S22 on 2m (not sure if they're still valid...)

Dave

[AdrianH]

Hello Mike;

I guess it will work it self out eventually, I have an old PDF and spreadsheet that came from BATC that had the numbering of channels, I also guessed that Evariste followed along with the idea.

I do like the fact that 500 333 and 250 use the same slots, well 500 may overlap a bit, but there was never any official statement for them previously, so I can only see it as good to stop some of the discussions as to where 500 should be! Same with 125 and below.

The one item I am very please about is the dropping of the overpower limit from the beacon by 1dB back to near the old level and the reduction in overpower indication from 500 to 3333KS. I noticed great reductions in some of the lower EIRP signals when everyone was pushing up at beacon level. It may not be liked by all users, but I believe it was a good move to keep the power consumption of the satellite to a reasonable level.

Adrian

p.s. Hi Dave good work done by the team.

[g0mjw]

I think we could it we used a 100kHz raster. That's less efficient but 10.493GHz would be CH30 - 10.494 CH40 etc up to 10.499 CH90 The narrow channels would then be the second digit, i.e. 100 kHz steps. So CH45 is 10.4945. Working out the output frequency is easy from the 1049XX where XX is the channel number however, not all channels are allowed. Input frequency is a little harder as you need to add 0.5MHz. But we are working to a 125kH raster, not 100kHz, and that won't be so easy on the grey cells.

Mike

[AdrianH]

I just had a reminisce of setting bandwidths on radios, when programming there used to be 25, 20 and 12.5KHz bandwidths as summarized by Wide, Normal and Narrow.

I am sure some with more brain power then me will have an idea.

Adrian

[g4hiz]

Dear all,

Good to see a nice clean band-plan.
For my own purposes, I describe the Narrow DATV segment in terms of channel 1 to 5 (low to high frequency), representing the 500kHz spacing. Given that the same 500kHz spacing is also used in the mixed Wide/Narrow segment, I shall use channel 1 to 9 for that. So we have M1 to M9 and N1 to N5.

Having a number system helps my quick logging. It would also be nice also to be able to say in simple terms "please QSY to ...'' when sometimes we get 'locked out' of a planned channel or 'plastered' on another, by those who choose not to follow good practice and look before uplinking, or simply may forget and leave the Tx on - as happens occasionally.

For narrower/wider channels, we just have to use common-sense, bearing in mind the plan.

Happy operating and keep well !

73
Jen G4HIZ

[g0mjw]

This makes sense too - we just need to implement something. W 1,2,3 and N 1-9 perhaps. I use presets, the ones currently in the Pluto as a drop down list and that's not a bad scheme. We could do the same with Portsdown maybe select symbol rate, select channel number and Dave does the magic translation for TX and RX.

One of the problems I find is when signals take a few seconds to start, two people clash as the channel was free when they both started, but there are still some stations, who I suspect do not speak English and therefore can not follow the chat and forums, who just send testcards anywhere regardless.

Mike

[G8GKQ]

Hi

I am concerned that we should not adopt an approach that would requires us to change if we make minor tweaks to the bandplan (for example increasing the bandwidth dedicated to 333 kS and lower SRs at the expense of wider transmissions).

How about we number the frequencies in 250 kHz steps from 10490 MHz as below? So:

10493.25 = Chan 13
10494.75 = Chan 19
10496.25 = Chan 25

The primary 333 kS channels would be 29, 31, 33, 35 and 37.

Channels 11 - 37 would all be valid 125 kS frequencies (although 11 - 28 should only be used if the upper end of the band was full).

Comments welcome!

Dave, G8GKQ