Opera 31 has 8 second symbol periods, so has a noise bandwidth of 0.125Hz.
Normalising this -38dB (in the ref 2500Hz) to the actual bandwidth
gives a S/N of +6dB
WSPR and JT4 when normalised in the same way come out at around 3dB
S/N. Now, assuming that -38dB / +6dB figure is based on the carrier
on period, and not the mean power (which on my measurements is exactly
50% duty cycle) suggests Opera is 3dB lower performing on its raw
decoding over WSJT. BUT, if the S/N is calculated based on the mean
power, then they are both equal. But since they are both non-coherent
tone detection modes with strong FEC, that's hardly surprising.
Andy
www.g4jnt.com
On 6 January 2012 20:49, Graham <[email protected]> wrote:
> That's ok Roger ..
>
> Rx speed is automatic ..... the speed select is for Tx only -
> mode select via frequency band
> No PC time lock required ...its free running
> OP31 expected round -38 dB s/n (ave) OP8 ~ -32 dB
>
> G..
>
>
>
> From: Roger Lapthorn
> Sent: Friday, January 06, 2012 8:38 PM
> To: [email protected]
> Subject: Re: LF: Opera questions
>
> Sorry Graham, another Opera question. Does the mode depend on PC timing in
> the same way WSPR does? I think not, but just checking.
>
> 73s
> Roger G3XBM
>
> On 6 January 2012 20:34, Roger Lapthorn <[email protected]> wrote:
>>
>> Thanks Graham.
>>
>> Does the software sort out if it is receiving an Op8 or Op31 transmission?
>> I.e. if I TX in Op31 do people have to listen in that speed too? I think not
>> as I copied SM6BHZ when my switch was set to Op31.
>>
>> Is it possible to establish the "effective sensitivity" when comparing
>> Opera against WSPR, QRSS3, 30 etc? I am unsure if the bandwidths of the
>> modes in which the S/N is shown for Opera is comparable. If more sensitive
>> than WSPR or QRSS30 even then this is definitely a very exciting new mode
>> for QRPers like me. It might also be fun for earth mode VLF tests too.
>>
>> 73s
>> Roger G3XBM
>>
>>
>> On 6 January 2012 20:25, Graham <[email protected]> wrote:
>>>
>>> Ok Roger
>>>
>>> The tx time is linked to the mode name OP2 = 2 mins , OP15 =
>>> 15 mins OP8 OP31 mins
>>>
>>> Who's on ? Yes p possibly , but that would need a web programmer ..
>>> but its only day 6 !
>>>
>>> you can check the PSK Report map to see who has tx /rx in the
>>> last 15 mins
>>>
>>> A book would be handy as it looks like its going to be popular
>>> , never seen so many beacons tx/rx on 136 !
>>>
>>> Left hand screen = local decodes
>>> Righ hand screen = decodes distributed over the web
>>>
>>> Not forgetting Mr Ros seems to code exceedingly good codes , as
>>> the advert says hi
>>>
>>> 73 -G..
>>>
>>> From: Roger Lapthorn
>>> Sent: Friday, January 06, 2012 8:10 PM
>>> To: [email protected]
>>> Subject: LF: Opera questions
>>>
>>> Somewhere I must have missed some information:
>>>
>>> How long does it take to send a beacon message in Opera8 and Opera31?
>>> Is it possible to have something like the WSPRnet database showing
>>> stations on each band monitoring and TXing? It helps to know someone is
>>> looking!
>>> Can we have a "read me" that explains what is meant to happen on the
>>> screen?
>>>
>>> Tried a brief transmission on 136 into my earth electrodes as my loop
>>> antenna is down without success (so far) but just had my first decode on RX
>>> in Opera8:
>>>
>>> 20:07 SM6BHZ 136 Op8 -19 dB 951 km @ 046 - not bad for 2 ground rods
>>> and no antenna!
>>>
>>> 73s and thanks for this interesting new mode Graham.
>>>
>>> Roger G3XBM
>>>
>>>
>>> --
>>> http://qss2.blogspot.com/
>>> http://g3xbm-qrp.blogspot.com/
>>> http://www.g3xbm.co.uk
>>> https://sites.google.com/site/sub9khz/
>>>
>>>
>>
>>
>>
>> --
>> http://qss2.blogspot.com/
>> http://g3xbm-qrp.blogspot.com/
>> http://www.g3xbm.co.uk
>> https://sites.google.com/site/sub9khz/
>>
>>
>
>
>
> --
> http://qss2.blogspot.com/
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
> https://sites.google.com/site/sub9khz/
>
>
|
