Where does this common spurious transmission come from? Is there a quality difference?
$begingroup$
I decided to see what my ham transmissions look like on an SDR and was kind of shocked to see how much leaks out. The waterfall display is split between two handhelds during transmit. There are a couple large energy spikes at +/- 800kHz to the 431.5MHz transmitting frequency.
Given that both radios spurious emissions are lined up and similar I'm guessing it is common and due to some sort of harmonic effect, possibly from implementing similar architecture.
Is there any negative to the less dispersed transmission of the bottom device/waterfall? The top half of the waterfall display is from a handheld transceiver that is much higher in quality than the one captured on the bottom half. Interestingly the SDR picks up the better handhelds audio much better even though voice communication between handheld devices is fine.
software-defined-radio rfi transceiver transmitter
asked Mar 30 at 22:32
RobCRobC
132
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RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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add a comment |
$begingroup$
I decided to see what my ham transmissions look like on an SDR and was kind of shocked to see how much leaks out. The waterfall display is split between two handhelds during transmit. There are a couple large energy spikes at +/- 800kHz to the 431.5MHz transmitting frequency.
Given that both radios spurious emissions are lined up and similar I'm guessing it is common and due to some sort of harmonic effect, possibly from implementing similar architecture.
Is there any negative to the less dispersed transmission of the bottom device/waterfall? The top half of the waterfall display is from a handheld transceiver that is much higher in quality than the one captured on the bottom half. Interestingly the SDR picks up the better handhelds audio much better even though voice communication between handheld devices is fine.
software-defined-radio rfi transceiver transmitter
asked Mar 30 at 22:32
RobCRobC
132
New contributor
RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
1
$begingroup$
Welcome to SE! Is there any chance the difference is related to overload of the SDR? For example, is there any indication that the ADC is being saturated? Also, are the radios putting out the same power, into similar antennas and coupling equally to the SDR?
$endgroup$
– Brian K1LI
Mar 30 at 22:47
$begingroup$
@BrianK1LI I was just using the 'low' settings on the handhelds about 3ft from the antenna. I just tried both about 30ft away and got the exact same waveforms.
$endgroup$
– RobC
Mar 30 at 22:55
$begingroup$
In that image, what software is that?
$endgroup$
– Mike Waters♦
2 days ago
1
$begingroup$
@MikeWaters GQRX, I've also been playing with OP25 which shows the actual QAM constellations which is pretty cool.
$endgroup$
– RobC
2 hours ago
$begingroup$
Thank you, I've edited your comment with a link to GQRX. :-) I want to see if it works with my Softrock RX Ensemble II in Linux Mint MATE 18.3.
$endgroup$
– Mike Waters♦
2 hours ago
add a comment |
$begingroup$
I decided to see what my ham transmissions look like on an SDR and was kind of shocked to see how much leaks out. The waterfall display is split between two handhelds during transmit. There are a couple large energy spikes at +/- 800kHz to the 431.5MHz transmitting frequency.
Given that both radios spurious emissions are lined up and similar I'm guessing it is common and due to some sort of harmonic effect, possibly from implementing similar architecture.
Is there any negative to the less dispersed transmission of the bottom device/waterfall? The top half of the waterfall display is from a handheld transceiver that is much higher in quality than the one captured on the bottom half. Interestingly the SDR picks up the better handhelds audio much better even though voice communication between handheld devices is fine.
software-defined-radio rfi transceiver transmitter
asked Mar 30 at 22:32
RobCRobC
132
New contributor
RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
I decided to see what my ham transmissions look like on an SDR and was kind of shocked to see how much leaks out. The waterfall display is split between two handhelds during transmit. There are a couple large energy spikes at +/- 800kHz to the 431.5MHz transmitting frequency.
Given that both radios spurious emissions are lined up and similar I'm guessing it is common and due to some sort of harmonic effect, possibly from implementing similar architecture.
Is there any negative to the less dispersed transmission of the bottom device/waterfall? The top half of the waterfall display is from a handheld transceiver that is much higher in quality than the one captured on the bottom half. Interestingly the SDR picks up the better handhelds audio much better even though voice communication between handheld devices is fine.
software-defined-radio rfi transceiver transmitter
software-defined-radio rfi transceiver transmitter
asked Mar 30 at 22:32
RobCRobC
132
New contributor
RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Mar 30 at 22:32
RobCRobC
132
New contributor
RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Mar 30 at 22:32
RobCRobC
132
New contributor
RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Mar 30 at 22:32
RobCRobC
132
asked Mar 30 at 22:32
RobCRobC
132
132
New contributor
RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
RobC is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
1
$begingroup$
Welcome to SE! Is there any chance the difference is related to overload of the SDR? For example, is there any indication that the ADC is being saturated? Also, are the radios putting out the same power, into similar antennas and coupling equally to the SDR?
$endgroup$
– Brian K1LI
Mar 30 at 22:47
$begingroup$
@BrianK1LI I was just using the 'low' settings on the handhelds about 3ft from the antenna. I just tried both about 30ft away and got the exact same waveforms.
$endgroup$
– RobC
Mar 30 at 22:55
$begingroup$
In that image, what software is that?
$endgroup$
– Mike Waters♦
2 days ago
1
$begingroup$
@MikeWaters GQRX, I've also been playing with OP25 which shows the actual QAM constellations which is pretty cool.
$endgroup$
– RobC
2 hours ago
$begingroup$
Thank you, I've edited your comment with a link to GQRX. :-) I want to see if it works with my Softrock RX Ensemble II in Linux Mint MATE 18.3.
$endgroup$
– Mike Waters♦
2 hours ago
add a comment |
1
$begingroup$
Welcome to SE! Is there any chance the difference is related to overload of the SDR? For example, is there any indication that the ADC is being saturated? Also, are the radios putting out the same power, into similar antennas and coupling equally to the SDR?
$endgroup$
– Brian K1LI
Mar 30 at 22:47
$begingroup$
@BrianK1LI I was just using the 'low' settings on the handhelds about 3ft from the antenna. I just tried both about 30ft away and got the exact same waveforms.
$endgroup$
– RobC
Mar 30 at 22:55
$begingroup$
In that image, what software is that?
$endgroup$
– Mike Waters♦
2 days ago
1
$begingroup$
@MikeWaters GQRX, I've also been playing with OP25 which shows the actual QAM constellations which is pretty cool.
$endgroup$
– RobC
2 hours ago
$begingroup$
Thank you, I've edited your comment with a link to GQRX. :-) I want to see if it works with my Softrock RX Ensemble II in Linux Mint MATE 18.3.
$endgroup$
– Mike Waters♦
2 hours ago
1
1
$begingroup$
Welcome to SE! Is there any chance the difference is related to overload of the SDR? For example, is there any indication that the ADC is being saturated? Also, are the radios putting out the same power, into similar antennas and coupling equally to the SDR?
$endgroup$
– Brian K1LI
Mar 30 at 22:47
$begingroup$
Welcome to SE! Is there any chance the difference is related to overload of the SDR? For example, is there any indication that the ADC is being saturated? Also, are the radios putting out the same power, into similar antennas and coupling equally to the SDR?
$endgroup$
– Brian K1LI
Mar 30 at 22:47
$begingroup$
@BrianK1LI I was just using the 'low' settings on the handhelds about 3ft from the antenna. I just tried both about 30ft away and got the exact same waveforms.
$endgroup$
– RobC
Mar 30 at 22:55
$begingroup$
@BrianK1LI I was just using the 'low' settings on the handhelds about 3ft from the antenna. I just tried both about 30ft away and got the exact same waveforms.
$endgroup$
– RobC
Mar 30 at 22:55
$begingroup$
In that image, what software is that?
$endgroup$
– Mike Waters♦
2 days ago
$begingroup$
In that image, what software is that?
$endgroup$
– Mike Waters♦
2 days ago
1
1
$begingroup$
@MikeWaters GQRX, I've also been playing with OP25 which shows the actual QAM constellations which is pretty cool.
$endgroup$
– RobC
2 hours ago
$begingroup$
@MikeWaters GQRX, I've also been playing with OP25 which shows the actual QAM constellations which is pretty cool.
$endgroup$
– RobC
2 hours ago
$begingroup$
Thank you, I've edited your comment with a link to GQRX. :-) I want to see if it works with my Softrock RX Ensemble II in Linux Mint MATE 18.3.
$endgroup$
– Mike Waters♦
2 hours ago
$begingroup$
Thank you, I've edited your comment with a link to GQRX. :-) I want to see if it works with my Softrock RX Ensemble II in Linux Mint MATE 18.3.
$endgroup$
– Mike Waters♦
2 hours ago
add a comment |
1 Answer
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$begingroup$
This is very likely to be be due to overload of the receiver. A quick, rough way to tell the difference:
- Tune your SDR receiver so the waterfall center frequency is not the same as the transmitter's frequency.
- Transmit.
- Check whether the spurs you see are symmetric about the transmitter's frequency or the receiver's frequency. This tells you which side generated them.
Also, if transmitting causes the entire waterfall to rise up then you definitely have an overload problem.
How to eliminate overload: First, make sure your receiver's RF gain is set to the minimum level, and AGC (if any) is off. Then try these things:
- Replace the transmitter's antenna with a dummy load.
- Replace the receiver's antenna with a dummy load or terminator, or if neither is available, just leave the antenna port unconnected.
- Get more distance.
answered Mar 30 at 23:46
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.5k33171
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$begingroup$
This is very likely to be be due to overload of the receiver. A quick, rough way to tell the difference:
- Tune your SDR receiver so the waterfall center frequency is not the same as the transmitter's frequency.
- Transmit.
- Check whether the spurs you see are symmetric about the transmitter's frequency or the receiver's frequency. This tells you which side generated them.
Also, if transmitting causes the entire waterfall to rise up then you definitely have an overload problem.
How to eliminate overload: First, make sure your receiver's RF gain is set to the minimum level, and AGC (if any) is off. Then try these things:
- Replace the transmitter's antenna with a dummy load.
- Replace the receiver's antenna with a dummy load or terminator, or if neither is available, just leave the antenna port unconnected.
- Get more distance.
answered Mar 30 at 23:46
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.5k33171
$endgroup$
add a comment |
$begingroup$
This is very likely to be be due to overload of the receiver. A quick, rough way to tell the difference:
- Tune your SDR receiver so the waterfall center frequency is not the same as the transmitter's frequency.
- Transmit.
- Check whether the spurs you see are symmetric about the transmitter's frequency or the receiver's frequency. This tells you which side generated them.
Also, if transmitting causes the entire waterfall to rise up then you definitely have an overload problem.
How to eliminate overload: First, make sure your receiver's RF gain is set to the minimum level, and AGC (if any) is off. Then try these things:
- Replace the transmitter's antenna with a dummy load.
- Replace the receiver's antenna with a dummy load or terminator, or if neither is available, just leave the antenna port unconnected.
- Get more distance.
answered Mar 30 at 23:46
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.5k33171
$endgroup$
add a comment |
$begingroup$
This is very likely to be be due to overload of the receiver. A quick, rough way to tell the difference:
- Tune your SDR receiver so the waterfall center frequency is not the same as the transmitter's frequency.
- Transmit.
- Check whether the spurs you see are symmetric about the transmitter's frequency or the receiver's frequency. This tells you which side generated them.
Also, if transmitting causes the entire waterfall to rise up then you definitely have an overload problem.
How to eliminate overload: First, make sure your receiver's RF gain is set to the minimum level, and AGC (if any) is off. Then try these things:
- Replace the transmitter's antenna with a dummy load.
- Replace the receiver's antenna with a dummy load or terminator, or if neither is available, just leave the antenna port unconnected.
- Get more distance.
answered Mar 30 at 23:46
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.5k33171
$endgroup$
This is very likely to be be due to overload of the receiver. A quick, rough way to tell the difference:
- Tune your SDR receiver so the waterfall center frequency is not the same as the transmitter's frequency.
- Transmit.
- Check whether the spurs you see are symmetric about the transmitter's frequency or the receiver's frequency. This tells you which side generated them.
Also, if transmitting causes the entire waterfall to rise up then you definitely have an overload problem.
How to eliminate overload: First, make sure your receiver's RF gain is set to the minimum level, and AGC (if any) is off. Then try these things:
- Replace the transmitter's antenna with a dummy load.
- Replace the receiver's antenna with a dummy load or terminator, or if neither is available, just leave the antenna port unconnected.
- Get more distance.
answered Mar 30 at 23:46
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.5k33171
answered Mar 30 at 23:46
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.5k33171
answered Mar 30 at 23:46
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.5k33171
answered Mar 30 at 23:46
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.5k33171
16.5k33171
add a comment |
add a comment |
RobC is a new contributor. Be nice, and check out our Code of Conduct.
RobC is a new contributor. Be nice, and check out our Code of Conduct.
RobC is a new contributor. Be nice, and check out our Code of Conduct.
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1
$begingroup$
Welcome to SE! Is there any chance the difference is related to overload of the SDR? For example, is there any indication that the ADC is being saturated? Also, are the radios putting out the same power, into similar antennas and coupling equally to the SDR?
$endgroup$
– Brian K1LI
Mar 30 at 22:47
$begingroup$
@BrianK1LI I was just using the 'low' settings on the handhelds about 3ft from the antenna. I just tried both about 30ft away and got the exact same waveforms.
$endgroup$
– RobC
Mar 30 at 22:55
$begingroup$
In that image, what software is that?
$endgroup$
– Mike Waters♦
2 days ago
1
$begingroup$
@MikeWaters GQRX, I've also been playing with OP25 which shows the actual QAM constellations which is pretty cool.
$endgroup$
– RobC
2 hours ago
$begingroup$
Thank you, I've edited your comment with a link to GQRX. :-) I want to see if it works with my Softrock RX Ensemble II in Linux Mint MATE 18.3.
$endgroup$
– Mike Waters♦
2 hours ago