Where does this common spurious transmission come from? Is there a quality difference? The Next CEO of Stack OverflowIs there a name for the demodulation technique described here using the parallax propeller?How to calculate if low-pass filtering is sufficient?Is there an advantage with having a DC bias for a FM radio transmission?Is there any way in which elevation *does* affect medium frequency (AM radio) transmissions?Is this the Correct Ferrite Core to Reduce RFI as a Common Mode Choke?
Can we say or write : "No, it'sn't"?
Math-accent symbol over parentheses enclosing accented symbol (amsmath)
Prepend last line of stdin to entire stdin
Why do airplanes bank sharply to the right after air-to-air refueling?
Do I need to write [sic] when a number is less than 10 but isn't written out?
Is it possible to use a NPN BJT as switch, from single power source?
Which one is the true statement?
Legal workarounds for testamentary trust perceived as unfair
Dominated convergence theorem - what sequence?
When you upcast Blindness/Deafness, do all targets suffer the same effect?
Proper way to express "He disappeared them"
I want to delete every two lines after 3rd lines in file contain very large number of lines :
Why did CATV standarize in 75 ohms and everyone else in 50?
A small doubt about the dominated convergence theorem
Is French Guiana a (hard) EU border?
Would a grinding machine be a simple and workable propulsion system for an interplanetary spacecraft?
How did people program for Consoles with multiple CPUs?
Help understanding this unsettling image of Titan, Epimetheus, and Saturn's rings?
Why does standard notation not preserve intervals (visually)
Is it ever safe to open a suspicious HTML file (e.g. email attachment)?
What did we know about the Kessel run before the prequels?
Is it my responsibility to learn a new technology in my own time my employer wants to implement?
How to get from Geneva Airport to Metabief, Doubs, France by public transport?
What flight has the highest ratio of time difference to flight time?
Where does this common spurious transmission come from? Is there a quality difference?
The Next CEO of Stack OverflowIs there a name for the demodulation technique described here using the parallax propeller?How to calculate if low-pass filtering is sufficient?Is there an advantage with having a DC bias for a FM radio transmission?Is there any way in which elevation *does* affect medium frequency (AM radio) transmissions?Is this the Correct Ferrite Core to Reduce RFI as a Common Mode Choke?
$begingroup$
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
New contributor
$endgroup$
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
New contributor
$endgroup$
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
4 hours ago
$begingroup$
@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
4 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
New contributor
$endgroup$
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
New contributor
New contributor
New contributor
asked 4 hours ago
RobCRobC
82
82
New contributor
New contributor
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
4 hours ago
$begingroup$
@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
4 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
4 hours ago
$begingroup$
@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
4 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
4 hours ago
$begingroup$
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
4 hours ago
$begingroup$
@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
4 hours ago
$begingroup$
@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
4 hours ago
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
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.
$endgroup$
add a comment |
Your Answer
StackExchange.ifUsing("editor", function ()
return StackExchange.using("mathjaxEditing", function ()
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
);
);
, "mathjax-editing");
StackExchange.ifUsing("editor", function ()
return StackExchange.using("schematics", function ()
StackExchange.schematics.init();
);
, "cicuitlab");
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "520"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
RobC is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fham.stackexchange.com%2fquestions%2f13163%2fwhere-does-this-common-spurious-transmission-come-from-is-there-a-quality-diffe%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
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.
$endgroup$
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.
$endgroup$
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.
$endgroup$
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 3 hours ago
Kevin Reid AG6YO♦Kevin Reid AG6YO
16.4k33170
16.4k33170
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.
RobC is a new contributor. Be nice, and check out our Code of Conduct.
Thanks for contributing an answer to Amateur Radio Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fham.stackexchange.com%2fquestions%2f13163%2fwhere-does-this-common-spurious-transmission-come-from-is-there-a-quality-diffe%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
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
4 hours ago
$begingroup$
@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
4 hours ago