Low-co.st, software-definable front end preselector for SDRs


Tom Crosbie G6PZZ
 

An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 23 April 2021 10:46
To: SDR-Radio@groups.io
Subject: [SDR-Radio] Low-cost, software-definable front end preselector for SDRs

 

ATEK1001

 

An open source, low-cost, software-definable front end preselector for SDRs and wideband receivers.

 

ATEK1001 | Crowd Supply

 

7 fixed-frequency, 1 external bypass, switchable

  • Band 1: 485-810 MHz
  • Band 2: 660-1125 MHz
  • Band 3: 960-1610 MHz
  • Band 4: 1420-2435 MHz
  • Band 5: 2070-3685 MHz
  • Band 6: 3245-5395 MHz
  • Band 7: 4660-7730 MHz

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--

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Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


jdow
 

I don't play around in those upper frequencies so I have no idea of the density of very powerful signals up there. For example would the 960-1610 filter, which is fixed tuned as they all are, be likely to improve GPS reception or not, for example? Can anyone relate some experience up there to help me fill this gap in my knowledge?

{^_^}

On 20210424 06:46:05, Tom Crosbie G6PZZ wrote:

An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 23 April 2021 10:46
To: SDR-Radio@groups.io
Subject: [SDR-Radio] Low-cost, software-definable front end preselector for SDRs

 

ATEK1001

 

An open source, low-cost, software-definable front end preselector for SDRs and wideband receivers.

 

ATEK1001 | Crowd Supply

 

7 fixed-frequency, 1 external bypass, switchable

  • Band 1: 485-810 MHz
  • Band 2: 660-1125 MHz
  • Band 3: 960-1610 MHz
  • Band 4: 1420-2435 MHz
  • Band 5: 2070-3685 MHz
  • Band 6: 3245-5395 MHz
  • Band 7: 4660-7730 MHz

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.



Lawrence Stoskopf
 

Might be a really big chip!  N0UU


On Apr 24, 2021, at 08:48, Tom Crosbie G6PZZ <tom@...> wrote:



An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 23 April 2021 10:46
To: SDR-Radio@groups.io
Subject: [SDR-Radio] Low-cost, software-definable front end preselector for SDRs

 

ATEK1001

 

An open source, low-cost, software-definable front end preselector for SDRs and wideband receivers.

 

ATEK1001 | Crowd Supply

 

7 fixed-frequency, 1 external bypass, switchable

  • Band 1: 485-810 MHz
  • Band 2: 660-1125 MHz
  • Band 3: 960-1610 MHz
  • Band 4: 1420-2435 MHz
  • Band 5: 2070-3685 MHz
  • Band 6: 3245-5395 MHz
  • Band 7: 4660-7730 MHz

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Jon Hudson
 

Below 2MHz, the SDRplay RSPs have up to 12 such bands: https://www.sdrplay.com/resources/RSPdxDatasheet.pdf

The RSPdx example- see page 2.  

Best regards, Jon


On 24 Apr 2021, at 14:48, Tom Crosbie G6PZZ <tom@...> wrote:



An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 23 April 2021 10:46
To: SDR-Radio@groups.io
Subject: [SDR-Radio] Low-cost, software-definable front end preselector for SDRs

 

ATEK1001

 

An open source, low-cost, software-definable front end preselector for SDRs and wideband receivers.

 

ATEK1001 | Crowd Supply

 

7 fixed-frequency, 1 external bypass, switchable

  • Band 1: 485-810 MHz
  • Band 2: 660-1125 MHz
  • Band 3: 960-1610 MHz
  • Band 4: 1420-2435 MHz
  • Band 5: 2070-3685 MHz
  • Band 6: 3245-5395 MHz
  • Band 7: 4660-7730 MHz

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Tom Crosbie G6PZZ
 

Thanks Jon,

I have the RSPdx but I’m looking for something to narrow the passband between RX and Ant and the ability to tune in between those frequencies, hoping to give a helping hand to wanted frequencies. Like old analogue preselectors. My main interest is in MW/SW BCB

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Jon Hudson via groups.io
Sent: 24 April 2021 15:31
To: main@sdr-radio.groups.io
Subject: Re: [SDR-Radio] Low-co.st, software-definable front end preselector for SDRs

 

Below 2MHz, the SDRplay RSPs have up to 12 such bands: https://www.sdrplay.com/resources/RSPdxDatasheet.pdf

 

The RSPdx example- see page 2.  

 

Best regards, Jon

 



On 24 Apr 2021, at 14:48, Tom Crosbie G6PZZ <tom@...> wrote:



An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 23 April 2021 10:46
To: SDR-Radio@groups.io
Subject: [SDR-Radio] Low-cost, software-definable front end preselector for SDRs

 

ATEK1001

 

An open source, low-cost, software-definable front end preselector for SDRs and wideband receivers.

 

ATEK1001 | Crowd Supply

 

7 fixed-frequency, 1 external bypass, switchable

  • Band 1: 485-810 MHz
  • Band 2: 660-1125 MHz
  • Band 3: 960-1610 MHz
  • Band 4: 1420-2435 MHz
  • Band 5: 2070-3685 MHz
  • Band 6: 3245-5395 MHz
  • Band 7: 4660-7730 MHz

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Simon Brown
 

So,

 

You’re after high-Q – why not build one? Nice variable capacitor and switchable inductor band like in days of old.

 

Also:

 

http://www.crosscountrywireless.net/preselector.htm

 

You could design this with friends, use an Arduino, talk to Console via a serial port etc.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Tom Crosbie G6PZZ
Sent: 24 April 2021 16:21
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Low-co.st, software-definable front end preselector for SDRs

 

Thanks Jon,

I have the RSPdx but I’m looking for something to narrow the passband between RX and Ant and the ability to tune in between those frequencies, hoping to give a helping hand to wanted frequencies. Like old analogue preselectors. My main interest is in MW/SW BCB

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Jon Hudson via groups.io
Sent: 24 April 2021 15:31
To: main@sdr-radio.groups.io
Subject: Re: [SDR-Radio] Low-co.st, software-definable front end preselector for SDRs

 

Below 2MHz, the SDRplay RSPs have up to 12 such bands: https://www.sdrplay.com/resources/RSPdxDatasheet.pdf

 

The RSPdx example- see page 2.  

 

Best regards, Jon

 

 

On 24 Apr 2021, at 14:48, Tom Crosbie G6PZZ <tom@...> wrote:



An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 23 April 2021 10:46
To: SDR-Radio@groups.io
Subject: [SDR-Radio] Low-cost, software-definable front end preselector for SDRs

 

ATEK1001

 

An open source, low-cost, software-definable front end preselector for SDRs and wideband receivers.

 

ATEK1001 | Crowd Supply

 

7 fixed-frequency, 1 external bypass, switchable

  • Band 1: 485-810 MHz
  • Band 2: 660-1125 MHz
  • Band 3: 960-1610 MHz
  • Band 4: 1420-2435 MHz
  • Band 5: 2070-3685 MHz
  • Band 6: 3245-5395 MHz
  • Band 7: 4660-7730 MHz

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Allan Isaacs
 

Why not simply make an analogue preselector Tom?

Twin gang 500pF tuning condenser, rotary switch, a few coils with a FET to handle the impedances. Keep the current consumption low, a few AA cells and an on-off switch.

I have a couple like this. One uses three 1m loops for tuning coils (L, M and S) and the other a set of ferrite rods.

You could keep it simple and feed it with a long wire tapped into the tuning coil. Metal box for screening etc

Allan G3PIY


From: main@SDR-Radio.groups.io [mailto:main@SDR-Radio.groups.io] On Behalf Of Tom Crosbie G6PZZ
Sent: 24 April 2021 16:21
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Low-co.st, software-definable front end preselector for SDRs

 

Thanks Jon,

I have the RSPdx but I’m looking for something to narrow the passband between RX and Ant and the ability to tune in between those frequencies, hoping to give a helping hand to wanted frequencies. Like old analogue preselectors. My main interest is in MW/SW BCB

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Jon Hudson via groups.io
Sent: 24 April 2021 15:31
To: main@sdr-radio.groups.io
Subject: Re: [SDR-Radio] Low-co.st, software-definable front end preselector for SDRs

 

Below 2MHz, the SDRplay RSPs have up to 12 such bands: https://www.sdrplay.com/resources/RSPdxDatasheet.pdf

 

The RSPdx example- see page 2.  

 

Best regards, Jon

 

 

On 24 Apr 2021, at 14:48, Tom Crosbie G6PZZ <tom@...> wrote:



An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

 


Roy VE7DH
 

jdow,

I have more than one GPS receiver/antenna in use here and when using HF or VHF transmissions it is not uncommon to lose the GPS signal over the transmission period.  One way I have found to mitigate that somewhat is to add extra low pass filtering at the TX end specifically to reduce the received harmonics at the GPS frequencies.

I have also used a 1550 Mhz LNB (Intelsat/Inmarsat) with internal SAW filter on a 1550 Mhz patch antenna to receive GPS signals. It works very well, both in received signal levels and also in resistance to the transmitters.

So, I would think that the filters in question would be helpful under those conditions.

regards, Roy


Siegfried Jackstien
 

not a big chip ... but a box with some relays ... a few coils and a bunch of caps (plus an arduino or similar getting frequency via cat command on comport or usb)

1 pf, 2 pf 4 .8. 16. 32.64 125 250 500

depending how dense you make the stepping in the coils you maybe can live with fewer caps

greeetz sigi dg9bfc

Am 24.04.2021 um 14:23 schrieb Lawrence Stoskopf via groups.io:

Might be a really big chip!  N0UU


On Apr 24, 2021, at 08:48, Tom Crosbie G6PZZ <tom@...> wrote:



An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 23 April 2021 10:46
To: SDR-Radio@groups.io
Subject: [SDR-Radio] Low-cost, software-definable front end preselector for SDRs

 

ATEK1001

 

An open source, low-cost, software-definable front end preselector for SDRs and wideband receivers.

 

ATEK1001 | Crowd Supply

 

7 fixed-frequency, 1 external bypass, switchable

  • Band 1: 485-810 MHz
  • Band 2: 660-1125 MHz
  • Band 3: 960-1610 MHz
  • Band 4: 1420-2435 MHz
  • Band 5: 2070-3685 MHz
  • Band 6: 3245-5395 MHz
  • Band 7: 4660-7730 MHz

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


jdow
 

SAW filters are MUCH narrower than the nearly octave band filters in this gadget.

{o.o}

On 20210425 06:36:20, Roy VE7DH wrote:
jdow,

I have more than one GPS receiver/antenna in use here and when using HF or VHF transmissions it is not uncommon to lose the GPS signal over the transmission period.  One way I have found to mitigate that somewhat is to add extra low pass filtering at the TX end specifically to reduce the received harmonics at the GPS frequencies.

I have also used a 1550 Mhz LNB (Intelsat/Inmarsat) with internal SAW filter on a 1550 Mhz patch antenna to receive GPS signals. It works very well, both in received signal levels and also in resistance to the transmitters.

So, I would think that the filters in question would be helpful under those conditions.

regards, Roy


Siegfried Jackstien
 

http://www.fukowa.de/9-band_preselektor.html

ready touse or as a kit

lcd controller, cat communication

http://www.fukowa.de/KW%209-Band%20Preselector%20public%20version.pdf

... only hambands (not for the sw listener) but needs no tuning but only selection with a relay

dg9bfc sigi


Am 24.04.2021 um 15:30 schrieb Simon Brown:

So,

 

You’re after high-Q – why not build one? Nice variable capacitor and switchable inductor band like in days of old.

 

Also:

 

http://www.crosscountrywireless.net/preselector.htm

 

You could design this with friends, use an Arduino, talk to Console via a serial port etc.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Tom Crosbie G6PZZ
Sent: 24 April 2021 16:21
To: main@SDR-Radio.groups.io
Subject: Re: [SDR-Radio] Low-co.st, software-definable front end preselector for SDRs

 

Thanks Jon,

I have the RSPdx but I’m looking for something to narrow the passband between RX and Ant and the ability to tune in between those frequencies, hoping to give a helping hand to wanted frequencies. Like old analogue preselectors. My main interest is in MW/SW BCB

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Jon Hudson via groups.io
Sent: 24 April 2021 15:31
To: main@sdr-radio.groups.io
Subject: Re: [SDR-Radio] Low-co.st, software-definable front end preselector for SDRs

 

Below 2MHz, the SDRplay RSPs have up to 12 such bands: https://www.sdrplay.com/resources/RSPdxDatasheet.pdf

 

The RSPdx example- see page 2.  

 

Best regards, Jon

 

 

On 24 Apr 2021, at 14:48, Tom Crosbie G6PZZ <tom@...> wrote:



An interesting link, Simon.

If only there was a similar kit covering VLF, LF, MW, SW.

BUT…it would have to tune in step with the SDR using Console.

 

Tom G6PZZ

 

From: main@SDR-Radio.groups.io <main@SDR-Radio.groups.io> On Behalf Of Simon Brown
Sent: 23 April 2021 10:46
To: SDR-Radio@groups.io
Subject: [SDR-Radio] Low-cost, software-definable front end preselector for SDRs

 

ATEK1001

 

An open source, low-cost, software-definable front end preselector for SDRs and wideband receivers.

 

ATEK1001 | Crowd Supply

 

7 fixed-frequency, 1 external bypass, switchable

  • Band 1: 485-810 MHz
  • Band 2: 660-1125 MHz
  • Band 3: 960-1610 MHz
  • Band 4: 1420-2435 MHz
  • Band 5: 2070-3685 MHz
  • Band 6: 3245-5395 MHz
  • Band 7: 4660-7730 MHz

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 


--

- + - + -

Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


--
- + - + -
Please use https://forum.sdr-radio.com:4499/ when posting questions or problems.


Roy VE7DH
 

You'll note that the SAW filter I mentioned is at 1550 Mhz, whereas GPS/Glonass, GNSS in general is at 1575 to 1600 Mhz.

So perhaps Saw filters are not really as narrow as they would pretend to be, though I do agree with your point about the octave wide filters.  In general I would say that any filtering would be an improvement over no filtering; if the device in question is sufficient  or desirable is yet to be determined.

regards, Roy


jdow
 

Oh, let's say it is somewhat difficult to get a SAW filter that is very wide. Presuming more modern materials and processes some significantly larger bandwidths may be feasible when I was working with them. (My teacher in this regard went on to become a chief engineer at Qualcomm reporting directly to the company president. Chuck was one of the very few PhDs I've met who were considered by all to be "lab safe".) The oscillator I mention when discussing my "oscillators don't" aphorism was 100kHz wide at around 300 MHz. It was "human size" for working with it. Size reductions and lithography improvements probably move it up to about 10 MHz wide at near 1,575.42 MHz. AND the GPS signal has some 50 dB of anti-jam margin. And noise or weak signal is just nature jamming the signal rather than enemy action. So, yeah, I can see it working "OK" for you. 10 MHz wide is totally different from 400 MHz wide at 500 or 600 MHz as far as letting in foreign signals. That is not saying it is poor. It is just saying it leaves a lot more room for interfering signals to get in. And I do not know what is up there and a problem at which frequencies. So I am wondering what a census of these regions of spectrum would show me if I setup to take a critical look.

(SAWs are cute gadgets. But for really narrow bandwidths they can get horridly large depending on material. But you CAN build some magical filters out of them. The design process is very much like designing FIR filters for SDRs.)

{^_^}

On 20210426 07:44:34, Roy VE7DH wrote:
You'll note that the SAW filter I mentioned is at 1550 Mhz, whereas GPS/Glonass, GNSS in general is at 1575 to 1600 Mhz.

So perhaps Saw filters are not really as narrow as they would pretend to be, though I do agree with your point about the octave wide filters.  In general I would say that any filtering would be an improvement over no filtering; if the device in question is sufficient  or desirable is yet to be determined.

regards, Roy