Date   

Re: Level Meter reading on alias products

Neil Smith G4DBN
 

Have a look at the PDFs at http://g4jnt.com/FDM-DU0_Notes.htm
(yes, that is a zero)
Neil G4DBN

On 13 Jul 2020, at 02:33, Paul Andrews <pandrews@...> wrote:

Where can I learn.about aliasing products.  I own 2 x FDM Duos.  #1 is on my 432 / 1296 MHz EME system.  I use a 28 MHz IF and transverters.  This is a awesome system for EME.

My #2 Duo is configured for 144 MHz and interconnected to a 10 GHz transverter.

This is my 1st try with 10 GHz so there might be multiple items to optimize.

Is using the Duo at 144 MHz a poor choice for weak signal work?

73 - Paul - W2HRO










On Sat, Jul 11, 2020, 14:57 Andy G4JNT <andy.g4jnt@...> wrote:
When using alias products on receive, ( eg at 144MHz), what does the level meter show when set to dBm ?

ie.  does it automatically take into account the SINC(X) loss






Re: Level Meter reading on alias products

Paul Andrews <pandrews@...>
 

Where can I learn.about aliasing products.  I own 2 x FDM Duos.  #1 is on my 432 / 1296 MHz EME system.  I use a 28 MHz IF and transverters.  This is a awesome system for EME.

My #2 Duo is configured for 144 MHz and interconnected to a 10 GHz transverter.

This is my 1st try with 10 GHz so there might be multiple items to optimize.

Is using the Duo at 144 MHz a poor choice for weak signal work?

73 - Paul - W2HRO










On Sat, Jul 11, 2020, 14:57 Andy G4JNT <andy.g4jnt@...> wrote:
When using alias products on receive, ( eg at 144MHz), what does the level meter show when set to dBm ?

ie.  does it automatically take into account the SINC(X) loss



Re: Phase noise or front end overload #elad

Clint Chron
 

Hi Patrick,

 

I have a home brew Antenna TR switch that I use with my Wellbrook mag loop antenna.  In the Antenna TR switch box, I have a AM band stop LC filter. I can bypass the LC filter as needed.  The AM band stop filter is the top board.  The same board (Mini-Kits) can also be used to build out a AM broadcast band high pass filter.

 

 

73

Clint

W7KEC

 

From: EladSDR@groups.io [mailto:EladSDR@groups.io] On Behalf Of Patrick Bouldin KM5L
Sent: Sunday, July 12, 2020 3:28 PM
To: EladSDR@groups.io
Subject: Re: [EladSDR] Phase noise or front end overload #elad

 

Got it Clint, now is the band stop filter in software, within SW2 or are you switching hardware in/out?


Re: Pulsing Inerference Question..

Clint Chron
 

Hi Dave,

 

I suspect that the 6.75 MHz signal is local to your QTH.  You could make a LC notch filter to notch out the signal.  Since it is LC, it would be fairly wide, but as long as it does not degrade the signal at 7.0 MHz, then it should take care of the problem.

 

73

Clint

W7KEC

 

 

From: EladSDR@groups.io [mailto:EladSDR@groups.io] On Behalf Of David KK7SS
Sent: Sunday, July 12, 2020 3:58 PM
To: EladSDR@groups.io
Subject: [EladSDR] Pulsing Inerference Question..

 

When I am on 40M I get a pulsing effect on the baseline noise level and affects the AGC.
I found this is because if a strong carrier on 6.750 MHz sending out a pulse about every 1 second.
This is in an frequency segment supposedley reserved for Aviation purposes

I do not know where this is based and I can't find it on any FAA maps.
It's too close to the start of the 40M band for a Rx filter to catch it..
Any suggestions on how to "notch" it out would be appreciated..

Dave KK7SS


Pulsing Inerference Question..

David KK7SS <d3j452@...>
 
Edited

When I am on 40M I get a pulsing effect on the baseline noise level plus it affects the AGC.
I found this is because of a strong carrier on 6.750 MHz sending out a pulse about every 1 second.
This is in a frequency segment supposedly reserved for Aviation purposes

I do not know where this is based and I can't find it on any FAA maps.
It's too close to the start of the 40M band for a Rx filter to catch it..
Any suggestions on how to "notch" it out would be appreciated..

Dave KK7SS


Re: Phase noise or front end overload #elad

Patrick Bouldin KM5L <patrick@...>
 

Got it Clint, now is the band stop filter in software, within SW2 or are you switching hardware in/out?


FDM DUO ..Plus.

Morris G1PIB
 

I have for sale FDM Duo ( Red ) plus a Hardrock 50 PA including integrated ATU .
This one is from garden shack so is not used as much as the DUO in my PC room.
As I stated in my last post proceeds go toward the S3..
Price for both only £700  ..all usb leads, usb stick, programing lead, Power lead , Mouse mat, PTT lead for PA
Duo is upto date regarding firmware etc. all in excelent condition and fully working.
Will post but prefer collection  ...
Thanks for reading and ..stay safe it's not over.......
Morris  g1pib in Somerset


Re: Phase noise or front end overload #elad

Clint Chron
 

Hi Patrick,

 

My band stop filter notches out all frequencies in the range of 550 KHz to 1600 KHz.   A high pass filter would also work to get rid of the AM broadcast station overload, but I wanted to listen to the frequencies of 200 KHz to 500 KHz.  It might be difficult to come up with a solution without knowing the source of your overload.  An occasional ADC Clip flash might not be indicative of your overload situation.

 

73

Clint

W7KEC

 

From: EladSDR@groups.io [mailto:EladSDR@groups.io] On Behalf Of Patrick Bouldin KM5L
Sent: Sunday, July 12, 2020 10:07 AM
To: EladSDR@groups.io
Subject: Re: [EladSDR] Phase noise or front end overload #elad

 

Hey Clint, thanks for responding. Gosh with so much crowding during field day I don't think I could answer those questions. I see the ADC flash now and then, always have, I thought I heard that was "normal". Didn't notice the DUO PK light but I'll start to look.

Your last comment, what is that, a high pass filter that blocks anything lower than 160 meters? Tell me about the filter!

Thanks and 73,
Patrick KM5L


Auto Notch

Brent Mcl
 

Dose this work on others radios on mine all  the audio is distorted no matter were the slide control sits  .


Re: Phase noise or front end overload #elad

Patrick Bouldin KM5L <patrick@...>
 

Hey Clint, thanks for responding. Gosh with so much crowding during field day I don't think I could answer those questions. I see the ADC flash now and then, always have, I thought I heard that was "normal". Didn't notice the DUO PK light but I'll start to look.

Your last comment, what is that, a high pass filter that blocks anything lower than 160 meters? Tell me about the filter!

Thanks and 73,
Patrick KM5L


Re: DUO up/down band change

Andy G4JNT
 

AH-HA____
Missed that.     192 + rssi etc.   or 0x32 + ....
and just checked the vol. settings and other bytes and yes, it's all been carefully thought-out to avoid 0x01 31 and 0x00 30 sequences - neat. 

As I never use dual VFO, I failed to appreciate my keypad only changes VFO-A.  If I read the status,  it could be arranged to change whichever VFO is in use.  But not really worth it for  microwave and VLF operations 



On Sun, 12 Jul 2020 at 17:28, Neil Smith G4DBN <neil@...> wrote:

The values in the 1024-byte spectrum have a range of 50 to 255 decimal, so you can't get a value lower than 0x32 as part of the spectrum, so the spectrum control block header pattern and parameter control block headers cannot be sent as spectrum values.

The values in the VFO A/B are encoded as 8-byte pseudo-ascii, so can't have a 0x01 or 0xF3 for example.

To guard against sync loss, you read in the number of bytes specified in the header and if any of the ASCII values are out of range, bail out of decoding and look for a new header.

It's a while since I messed with interfacing, but it worked OK and seemed robust, but the test would be to cause some glitches and see if the decoder can recover.  If you read in a 1024 byte spectrum and byte 3 was 0x00 because of a long glitch, then so long as your parser can restart decoding at that point and doesn't have to discard the buffer, you would be able to recover gracefully.  Otherwise just ditch the lot and scan for another valid header frame.

Neil G4DBN


On 12/07/2020 16:48, Andy G4JNT wrote:
Having looked at the EXTIO protocol I'm now a bit confused.
There is an attempt to make a header for Spectrum and  Parameter data  ,   0x00 30 [30 30 34 30]   and  0x01 31 [3F 31 30 30] respectively, but as far as I can see it is not necessarily unique;   there is nothing to stop that series of bytes appearing in either the body of the spectrum data, which is just 8 bit byte values, or in some of the parameter fields.

I feel sure I've missed some point somewhere, as it clearly does work in practice with the Blue Duo etc,  but why doesn't framing go wrong ?

If the frame pattern is unique, then extracting just small amounts of parameter data is merely a case of looking for the frame, then counting bytes until the wanted ones arrive.   A small circular buffer a low as 31 bytes long would suffice for that - and any small processor like a PIC  could do it.



On Sat, 11 Jul 2020 at 08:24, Giovanni Franza <gfranza@...> wrote:

[Edited Message Follows]

Hi Andy,
the band of the spectrum is 192kHz and the bins are of 192/1024 kHz, because 192 kS/s is the sampling rate at which the internal SDR operates.
On the spectrum you can see the effect of the windowing as "shoulders" on the ending of the spectrum.
In BlueDUO I use and display only 160 kHz because I prefer not to show the part of band afflicted by the windowing.
Do not trust the spectrum timing. It is computed when the internal cpu has time, not on precise istants, even if the timings are more or less those.
Reards,

Giovanni - HB9EIK
_._,_._,


Re: DUO up/down band change

Giovanni Franza
 

Hi Andy,
for the sketch length the problem is not only the buffer length (see later) but also variables and code itself.
For the buffer: sometimes the protcol has been modified, and it is possibile that more parameters will be added in the future.
If you plan to use a buffer for data receprion, remember to use a bigger one or to limit byte reading to buffer length
and to discard other data if the protocol report a length greater than buffer length.
My sketch is far perfect, it was built ony to solve a specific problem, and I left code only to help people that are willing to erite ther own code.
Regards,

Giovanni - HB9EIK


Re: DUO up/down band change

Giovanni Franza
 

Hi Neil,
your explanation is perfect, both in BlueDUO and other projects I don't have problem with sincronization, even if I start serial progam, and receprion, at "wrong time".

Giovanni - HB9EIK


Re: DUO up/down band change

Neil Smith G4DBN
 

The values in the 1024-byte spectrum have a range of 50 to 255 decimal, so you can't get a value lower than 0x32 as part of the spectrum, so the spectrum control block header pattern and parameter control block headers cannot be sent as spectrum values.

The values in the VFO A/B are encoded as 8-byte pseudo-ascii, so can't have a 0x01 or 0xF3 for example.

To guard against sync loss, you read in the number of bytes specified in the header and if any of the ASCII values are out of range, bail out of decoding and look for a new header.

It's a while since I messed with interfacing, but it worked OK and seemed robust, but the test would be to cause some glitches and see if the decoder can recover.  If you read in a 1024 byte spectrum and byte 3 was 0x00 because of a long glitch, then so long as your parser can restart decoding at that point and doesn't have to discard the buffer, you would be able to recover gracefully.  Otherwise just ditch the lot and scan for another valid header frame.

Neil G4DBN


On 12/07/2020 16:48, Andy G4JNT wrote:
Having looked at the EXTIO protocol I'm now a bit confused.
There is an attempt to make a header for Spectrum and  Parameter data  ,   0x00 30 [30 30 34 30]   and  0x01 31 [3F 31 30 30] respectively, but as far as I can see it is not necessarily unique;   there is nothing to stop that series of bytes appearing in either the body of the spectrum data, which is just 8 bit byte values, or in some of the parameter fields.

I feel sure I've missed some point somewhere, as it clearly does work in practice with the Blue Duo etc,  but why doesn't framing go wrong ?

If the frame pattern is unique, then extracting just small amounts of parameter data is merely a case of looking for the frame, then counting bytes until the wanted ones arrive.   A small circular buffer a low as 31 bytes long would suffice for that - and any small processor like a PIC  could do it.



On Sat, 11 Jul 2020 at 08:24, Giovanni Franza <gfranza@...> wrote:

[Edited Message Follows]

Hi Andy,
the band of the spectrum is 192kHz and the bins are of 192/1024 kHz, because 192 kS/s is the sampling rate at which the internal SDR operates.
On the spectrum you can see the effect of the windowing as "shoulders" on the ending of the spectrum.
In BlueDUO I use and display only 160 kHz because I prefer not to show the part of band afflicted by the windowing.
Do not trust the spectrum timing. It is computed when the internal cpu has time, not on precise istants, even if the timings are more or less those.
Reards,

Giovanni - HB9EIK
_._,_._,


Re: DUO up/down band change

Andy G4JNT
 

Having looked at the EXTIO protocol I'm now a bit confused.
There is an attempt to make a header for Spectrum and  Parameter data  ,   0x00 30 [30 30 34 30]   and  0x01 31 [3F 31 30 30] respectively, but as far as I can see it is not necessarily unique;   there is nothing to stop that series of bytes appearing in either the body of the spectrum data, which is just 8 bit byte values, or in some of the parameter fields.

I feel sure I've missed some point somewhere, as it clearly does work in practice with the Blue Duo etc,  but why doesn't framing go wrong ?

If the frame pattern is unique, then extracting just small amounts of parameter data is merely a case of looking for the frame, then counting bytes until the wanted ones arrive.   A small circular buffer a low as 31 bytes long would suffice for that - and any small processor like a PIC  could do it.



On Sat, 11 Jul 2020 at 08:24, Giovanni Franza <gfranza@...> wrote:

[Edited Message Follows]

Hi Andy,
the band of the spectrum is 192kHz and the bins are of 192/1024 kHz, because 192 kS/s is the sampling rate at which the internal SDR operates.
On the spectrum you can see the effect of the windowing as "shoulders" on the ending of the spectrum.
In BlueDUO I use and display only 160 kHz because I prefer not to show the part of band afflicted by the windowing.
Do not trust the spectrum timing. It is computed when the internal cpu has time, not on precise istants, even if the timings are more or less those.
Reards,

Giovanni - HB9EIK


Re: Phase noise or front end overload #elad

Clint Chron
 

Hi Patrick,

 

If the problem signal was adjacent band, then external band pass filters will most likely help.  You need to know the source of the signal that was causing the problem.  If the signal was in-band, then a band pass filter will probably not help.

Did you see the “PK” light on the front of the Duo or the ADC Clip light on the SW-2 software?

 

At my home QTH, I get overload from the strong AM broadcast stations that are about 12 miles from my house.  I have an external AM band-stop filter on my Duo that gets rid of the overload.

 

73

Clint

W7KEC

 

From: EladSDR@groups.io [mailto:EladSDR@groups.io] On Behalf Of Patrick Bouldin KM5L
Sent: Sunday, July 12, 2020 7:33 AM
To: EladSDR@groups.io
Subject: [EladSDR] Phase noise or front end overload #elad

 

Greetings!

Hey I started out using the FDM DUO for Field day, almost all CW. Had to stop because with so much traffic something was creating a lot of phase noise, or just overload of some kind.

Have others experienced this? I don't have any of the external bandpass filters, maybe this will solve, what do you think?

73, 
Patrick KM5L


Phase noise or front end overload #elad

Patrick Bouldin KM5L <patrick@...>
 

Greetings!

Hey I started out using the FDM DUO for Field day, almost all CW. Had to stop because with so much traffic something was creating a lot of phase noise, or just overload of some kind.

Have others experienced this? I don't have any of the external bandpass filters, maybe this will solve, what do you think?

73, 
Patrick KM5L


Re: ART-120 Failure

Charles Ristorcelli
 

How did you open the fuse cap?

Did you use some type of sharp object to remove it?

Mine will not remove by just pulling or pressing it.

I am afraid of damaging it if I use a screwdriver or needle nose plioers.

--
73 de NN3V


Re: ART-60 Spectrum display #duo-art

Simon
 

Ah ok!!!!

Then u need an active loop antenna..lz1aq amp design is GOOD  

Use 4 square loops plus one set at 90 degrees to get 90 degree steering..and also a preferred homebrew noise canceller/ phaser..

I live in very built up london..s3-5 noise on active loop on 160..s5-7 on tx mag loop..

Simon 

On 11 Jul 2020, at 18:33, David KK7SS <d3j452@...> wrote:



Simon,
That's with the dummy load... just internally generated noise!
Quite noisy on my vertical - S6-S9 on 40M !
100ft from the main road intersection, street lights, power lines, traffic lights, etc.
Mercury and Sodium lights at the school 280 ft away!
And one of my neighbors has a plasma TV..
But it could be worse - I could be in an housing area with antenna bans  LOL

Dave KK7SS


Level Meter reading on alias products

Andy G4JNT
 

When using alias products on receive, ( eg at 144MHz), what does the level meter show when set to dBm ?

ie.  does it automatically take into account the SINC(X) loss


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