Re: Using TinySA as field strength meter
You cannot convert to V/m without having a calibrated antenna or at least knowing the antenna factor for the antenna in use.
Originally you said that all you wanted to do was see how much improvement the reflector gave, that is a relative measure that you can read directly from the TinySA in dB, you do not need to know the actual V/m.
73
Jeff G8HUL
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Pier HB9IIA Sent: 02 September 2024 19:01 To: [email protected]Subject: Re: [tinysa] Using TinySA as field strength meter Thank you for your input Herb. How can I measure V/m or W/cm^2 with the Tiny directly? I‘m able to measure the signal in dbm and can the convert to mW or uV. How can I convert to V/m or W/cm^2?
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Re: Using TinySA as field strength meter
https://www.aliexpress.com/item/1005006338594491.html
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Re: Using TinySA as field strength meter
Would you please post the actual link for that Ali Express antenna. I can't seem to find it. Thanks
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How far the tiny SA can detect a signal depends entirely on the strength of the signal, which depends upon the power of the signal source and the radiation efficiency of the source antenna.? (And, of course, the distance between the signal source and the tiny SA.)? At the moment I am looking at the signal from an FM broadcast station I know to be over 15 kilometers from me.? I have also been looking at a source of interference to my ham radios on 144 MHz.? That signal disappears if I go to the opposite end of the house, so it seems that interfering signal is almost certainly inside my house.? Whatever it is, the tinySA will detect it from maybe 20 meters away.? Again, it depends entirely upon the strength of the signal.
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Re: Using TinySA as field strength meter
Thank you for your explanation Herb, I appreciate that. You have the perfect background to answer that question. I assume that the calibrated field probe would be an antenna from wich you know the field strenght in V/m at a defined distance? You would than measure in dbm=>uV=>with correction factor into V/m.
Could someone build or simulate a pricise field strenght calibration probe themself i.e. a coil from wich you know the theoretical field strength at a certain distance and then use that to set up the correction table?
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I have updated the to version 0.11.7.? This has a number of enhancements as well as bugfixes.
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NOTE: This release requires the updated config database QtTSAprefs.db and is not backwards-compatible with earlier database versions.
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- Much faster stopping on slow sweeps when 'stop' is pressed.
- Measurement Fn uses the new scanraw auto-repeat option, but is backwards compatible with firmware older than 1.4.177.? It scans significantly faster except on slow scans, where there is only a small speed improvement.
- Zero span now working as well as it can without re-coding or the ability to control triggering and sweep speed.
- Detect if there are several connected tinySA, and allow choosing the one to use in 'preferences' dialogue (request by Herb Walker).
- Can set the maximum scan frequency above default of 6GHz in 'preferences' dialogue (request by @ashjmckenzie ).
- 'Max' trace is now permanent hold until scanning stopped/restarted, instead of a decaying max (request by @CliveTombs).
- Marker min/max detection frequency boundary lines added (request by @CliveTombs).
- Sync Time to PC Time setting, AverageBox & Sample repeat added to config database so now remember setting.
- Removed padding from the GUI display to make more screen room for scan.
- Set Scan to Graph button (<>) added.? Display can be moved/zoomed with mouse drag and then scan set to that by pressing the button.
- Clicking a marker centres the sweep freq onto that marker.
- Units on freq axis now set automatically (changed preferences database to Hz instead of MHz).
I will update the QtTinySA Wiki with some info on how to save existing preset frequencies/markers, update them to Hz and import to the new database.? Unless someone else beats me to it :-)
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Ian G4IXT
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Re: Using TinySA as field strength meter
Personally, I'd set the SA to read in dBm.? You may prefer something different if you don't understand logarithms.? If nothing is moved, you can also invoke the "delta" function in whatever units you prefer.? That would make it easier to immediately see the results of adding your reflector.? Remember, +3 dB is 2X the directed power and -3 dB is 0.5X the directed power.? For a properly placed reflector of the proper length, I'd expect around a +3 dB increase in directed power.??
Dave - W?LEV
So what settings should be used for the comparative measurement?
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Re: Using TinySA as field strength meter
On Mon, Sep 2, 2024 at 11:12 AM, Pier HB9IIA wrote:
How can I measure V/m or W/cm^2 with the Tiny directly? I‘m able to measure the signal in dbm and can the convert to mW or uV. How can I convert to V/m or W/cm^2?
? I worked at a regulatory agency that tested to commercial and military standards.? We used calibrated field probes that produced signal levels on the spectrum analyzer that were calibrated in V/m or W/cm^2.
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? The tinySA Ultra under LEVEL->UNIT will display measurement units in V or Watts.? The calibrated field probe will come with conversion factors to add to the displayed value to convert to V/m or W/cm^2.? Regulatory agencies require precise measurement levels.? Unless you are using the tinySA in a commercial application I doubt if the expense of a calibrated field probe is worth it to you.
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? ?You can use TRACE->CALC OFF->TABLE-TRACE to enter the probe correction factors into the tinySA Ultra so that the levels are effectively displayed in units of V/m or W/cm^2.
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Herb
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Re: Using TinySA as field strength meter
Thank you for your input Herb.
How can I measure V/m or W/cm^2 with the Tiny directly? I‘m able to measure the signal in dbm and can the convert to mW or uV. How can I convert to V/m or W/cm^2?
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Re: Using TinySA as field strength meter
On Mon, Sep 2, 2024 at 07:29 AM, Vasy Vasii wrote:
This is the price for a "branded" antenna with worse characteristics
? ?The price of an antenna usually reflects how well characterized it is and whether it comes with accurate conversion factors for converting the spectrum analyzer readings from say dBuV to dBuV/m.?
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? ?The conversion factor + cable loss + external amplifier gain gives you a corrected field strength reading at the measurement frequency.? You generally only need this level of accuracy for regulatory measurements or academic papers.
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Herb
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Re: Using TinySA as field strength meter
On Mon, Sep 2, 2024 at 09:40 AM, John Leach K0JHL wrote:
So what settings should be used for the comparative measurement?
You are doing an A/B comparison with and without the reflector so your settings and set-up should vary as little as possible.?
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1. Same antenna length.
2. Same measurement location.
3. Same spectrum analyzer settings.
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? ?As a baseline capture and store the spectrum analyzer trace without the reflector.? Then attach the reflector and run a second trace.? The difference between the two traces should be a relative indication of the effectiveness of the reflector.
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Herb
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On Mon, Sep 2, 2024 at 09:16 AM, Ian Jefferson wrote:
I did a little inspection of the returned data and decided it was '}{', have I got that wrong Erik?
Just a bit, end of scan is '}'
start of scan is '{'
After an abort you only get? '}'
--
Designer of the tinySA
For more info go to
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Re: Using TinySA as field strength meter
So what settings should be used for the comparative measurement?
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The way I have done it in QtTinySA ( which I just finished testing in Windows and am about to "release") is to put the 'stop scanning' command from the GUI into a FIFO queue and then detect the presence of it in the measurement thread, because that's thread-safe.? The thread then sends the 'abort' command and empties the buffer.? It takes it about 2 seconds to stop, even with the lowest RBW slow scan.
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I detect the "end of scan" character to ensure that the interpretation of the reading's frequency is not "out of sync" with the actual hardware.? But I may have misunderstood the "end of scan" character - I did a little inspection of the returned data and decided it was '}{', have I got that wrong Erik?
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QtTinySA v0.11.7 with firmware 1.4.177 is noticeably faster scanning when the scan speed is higher, because of the reduced overhead from not having to send the scan command for every sweep.
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Ian
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Dear all,?
I would like to detect the behavior of uploading a file using a 5GHz WiFi network. To do this, I use a ultra tinySA with an antenna plugged into "RF port" to measure the power (in Watts) of the RF signal during the upload process. It's normal that the signal strength is clearly dependent on the distance and the ?antenna used.
I've noticed that the power drops from nanowatts to picowatts when the distance between the tinySA and my laptop increases from being next to the laptop to about three to five meters away. I experimented with a directional antenna (like ), an omnidirectional WiFi antenna, and the antenna attached in the tinySA box. The antenna attached to the tinySA provided the best range, still detecting the signal at approximately 5 meters.
Could you please advise on how far the tinySA can typically detect a signal (in my case is the laptop's upload signal or signal from a remote control of some car toys)? Additionally, if I need to detect a signal exceed to 20-30 meters, is it applicable with tinySA and what setup would you recommend (e.g., better antennas with higher gain, device settings, etc.)?
Thank you very much for your help.
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Re: Using TinySA as field strength meter
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This is the price for a "branded" antenna with worse characteristics
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Re: Using TinySA as field strength meter
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What do you think of this antenna?
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Toni,
There is a "end of scan" currently being send after each automatically repeated scanraw ( '}'), why don't you use that ?
You can send an abort command directly after receiving the "end of scan" and discard anything being send till the next "end of scan"
--
Designer of the tinySA
For more info go to
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Erik,?
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Thank You.
Yes, You just enhanced my idea, that is final result which I would like to have:
- to be able to request an explicit number of scans and after TinySA ultra execute that explicit number of scans to respond in usual described formatted set of data
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Please if you could plan implementation of that feature in next firmare update.
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p.s. watchdog/'restart' command is also working as described on wiki.
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Br,
Toni
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Re: Using TinySA as field strength meter
The OP was only interested in a relative measurement, so the calibration of the antenna is not relevant in this case. The TinySA will give very god relative measurements. The precautions that W0LEV outlines still apply.
73
Jeff G8HUL
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of hwalker Sent: 01 September 2024 19:56 To: [email protected]Subject: Re: [tinysa] Using TinySA as field strength meter On Sun, Sep 1, 2024 at 10:06 AM, W0LEV wrote: the TinySAs can be used as a field strength "meter" with good accurate readout of the far field RF energy. The caveat is that field strength is measured with a units qualifier such as V/m or W/cm^2. The transducer attached to the meter is calibrated for such units. The tinySA with its telescopic antenna will only display relative signal amplitudes. This may be enough to show comparative differences in the OP's reflector configurations, but not enough to provide accurate field strength numbers. A calibrated dipole or log-periodic antenna will come with correction factors that can be added to the tinySA to give corrected values in V/m. Such antennas generally cost much more than the tinySA itself. The antennas also would not fit the reflector scheme proposed by the OP. Herb
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Sam Reaves
Jim Allyn - N7JA
Pier HB9IIA