[hpsdr] Multiple RX issues

Mon Oct 13 14:21:41 PDT 2014

Hi Bob, 

It’s been a while since I’ve looked at the issue with regard to the Atlas-based system, but I seem to recall that the reduction of the number of receivers on Mercury was mostly due to the inability of the Atlas bus to adequatley handle the data rates at the higher sampling rates and multiple receiver configurations everyone was seeking.  The reduction from four receivers in the Mercury firmware occurred at the same time that the new polyphase-filter receiver modules were implemented and the higher sampling rate options were implemented.  We did have a four receiver version of Mercury firmware, v3.2 I believe, but it was limited to 192ksps for sampling rate and did not have the numerous C&C selectable options that the current Mercury firmware provides.  

To utilize the full potential of cuSDR (or dual Rx PowerSDR with PureSignal for that matter) it is necessary to use platforms other than the Atlas-based HPSDR radio, at least at the present time.  

There was some effort a while back, I believe, to implement PureSignal for the Atlas-based rigs but it has not been successfully achieved to my knowledge.  The simple truth is that the high data rates that are required for multiple receivers (more than 3) are accommodated better with single-board platforms (Hermes, Angelia, Orion) because they do not have the speed issues that are associated with the Atlas bus.  cuSDR should work fine for you as long as you limit yourself to 3 receivers when running an Atlas-based system.  PowerSDR internally limits things to 2 receivers when the “HPSDR” hardware (Atlas-based system) is selected, I think; other hardware selections (non-Atlas-based selections) within PowerSDR permit automatic use of greater numbers of receivers, as for example, to support PureSignal, etc.  

73, Joe K5SO

On Oct 13, 2014, at 2:49 PM, Bob Cowdery wrote:

> Hi Joe,
> 
> Well, that certainly explains it and why Rx4 is all zeros. I really
> hadn't appreciated that as I took the spec at face value and seeing
> CuSDR allowing 7 I thought it must be implemented. Is that a hardware
> limitation with Atlas do you know?
> 
> 73, Bob G3UKB
> 
> On 13/10/2014 21:34, Joe Martin K5SO wrote:
>> Hi Bob, 
>> 
>> Mercury v3.4 implements a maximum of 3 receviers in the firmware.  
>> 
>> Metis_v2.6, which I think you said you are using, allows for 4 receivers, in principle, but that does you no good on the Atlas-based system as Mercury firmware limits the max number of receivers to 3.  
>> 
>> 73, Joe K5SO
>> 
>> On Oct 13, 2014, at 2:18 PM, Bob Cowdery wrote:
>> 
>>> ***** High Performance Software Defined Radio Discussion List *****
>>> 
>>> Just confirmed that the I and Q data for RX4 is all zeros so that has to
>>> be coming out the hardware. Any ideas anyone?
>>> 
>>> 73, Bob G3UKB
>>> 
>>> On 13/10/2014 20:43, Bob Cowdery wrote:
>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>> 
>>>> Hi Warren,
>>>> 
>>>> Thanks for the input. I'm only running 48K and I set CuSDR to 48K as
>>>> well. I don't think its running out of steam. CPU is about 10% with 4RX
>>>> and network about 25%, but only goes up to 27% with 5 RX. Still higher
>>>> than I expected though.
>>>> 
>>>> The strange thing is that with 4 RX, the first 3 still work correctly
>>>> and there are no dropped packets or sync errors. I've not checked the
>>>> actual data of the 4th RX yet but I'm assuming its all very low numbers
>>>> close to zero as there is no audio and panadapter flat lines at the
>>>> bottom on CuSDR.
>>>> 
>>>> Just to see what happened I tried 6 and 7 receivers, still no dropped
>>>> packets, rubbish out the audio and usage 15% CPU 31% network. I still
>>>> think something is going funny in the firmware.
>>>> 
>>>> 73, Bob G3UKB
>>>> 
>>>> 
>>>> On 13/10/2014 19:57, Warren C. Pratt wrote:
>>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>>> 
>>>>> Hi Bob,
>>>>> 
>>>>> Perhaps your problem with sync errors when the 5th receiver is enabled
>>>>> is that the 100Mbit interface will not support five receivers at
>>>>> 384K.  IF you are trying that at 384K, you'll need to back down to 192K.
>>>>> 
>>>>> I'm not sure I understand exactly what you mean about "no data and
>>>>> thus no audio."  If you are running PowerSDR, it only generates audio
>>>>> for RX1 (and its sub-receiver) and for RX2.  RX3, RX4, and RX5 are
>>>>> used for things such as the stitched panadapter, PureSignal, and
>>>>> diversity reception.  I'm not familiar enough with cuSDR to comment
>>>>> there.
>>>>> 
>>>>> Hope that helps.
>>>>> 
>>>>> 73,
>>>>> Warren  NR0V
>>>>> 
>>>>> On 10/13/2014 11:52 AM, Bob Cowdery wrote:
>>>>>> ***** High Performance Software Defined Radio Discussion List *****
>>>>>> 
>>>>>> Hi,
>>>>>> 
>>>>>> I've been playing around with multiple receivers on some software I'm
>>>>>> writing and something strange is going on.
>>>>>> 
>>>>>> I can direct audio from each receiver to different local output devices
>>>>>> left/right/both so I can hear what's going on on each RX. Everything is
>>>>>> fine up to 3 receivers, the 4th receiver gives no data and thus no audio
>>>>>> and the 5th starts giving sync errors i.e. the 7f7f7f is not where it
>>>>>> should be.
>>>>>> 
>>>>>> I installed and ran up CuSDR32 and I get exactly the same result. I
>>>>>> can't hear what's going on but RX4 has no panadapter output and RX5
>>>>>> continually flashes the sync indicator.
>>>>>> 
>>>>>> I've not updated the hardware for a while, using Metis 2.6 and Mercury
>>>>>> 3.4. Anyone know if there are any known issues with these versions?
>>>>>> Failing that is anybody getting receivers above 3 working with those
>>>>>> versions.
>>>>>> 
>>>>>> Thanks for any help
>>>>>> 
>>>>>> 73 Bob (G3UKB)
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