WARNING: Measuring the spectral purity of a transmitter
A word of warning for those that want to measure the spectral purity of their transmitter.
As the tinySA is specced to accept +10dBm without attenuation and +30dBm for some seconds with maximum attenuation you may be tempted to connect the output of the transmitter to the tinySA, set the tinySA to max hold and transmit for a short time, long enough for one sweep.
Even when your transmitter stays below +30dBm you risk making a wrong measurement, or even worse, if you have attenuation on automatic, destroy the tinySA as the tinySA will only adjust (e.g. increase) the attenuation for the next sweep.
The spur free dynamic range of the tinySA is a bit above 70dB with an RBW of 300kHz. This means that any signal that is more than 70dB above the noise floor will cause internally generated harmonics.
Let's take an example:
Without attenuation and with an RBW of 300kHz the noise floor is at -95dBm. With an input signal of 0dBm you are 25dB above the spur free dynamic range so there will be internally generated harmonics.
For a good measurement you should apply 25dB of attenuation?
Make sure to update the FW of you first batch tinySA as the newer FW contains an overload warning (the marker info turns red) to help you make a good measurement.
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Re: tinySA has been listed in Alibaba store
On Thu, Jul 23, 2020 at 01:23 PM, Shirley Dulcey KE1L wrote:
If this first run is well received, I expect that the US companies that are reselling the NanoVNA-H (I know about R&L and Gigaparts) will make large purchases of the tinySA and resell it. They're a good alternative for US residents; delivered cost from R&L is about the same as ordering from Hugen's Alibaba store and you get it faster.
? Although currently out of stock, R&L Electronics in the US has announced that they will be selling the tinySA:? ??? ?My ham radio group has purchased many hugen products from R&L over the last year and have been very satisfied with their customer service and speed of delivery. ?- Herb
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On the other hand if vat or duty is due according to said countries rules. We, as in the customer, ought to pay it.
We should not avoid it. It pays towards our society services after all.
Otherwise we are as corrupt as other countries despotic leaders ..........just in a smaller way. Nevertheless still corrupt!
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On 18 Aug 2020, at 16:52, EB4APL <eb4apl@...> wrote:
?Today DHL delivered me a couple of tinySA.
Still no powered it up, but I want to note that the packaging was really good, thanks Maggie.
The only negative comment is about DHL. DHL is a carrier and also a customs clearance agent and they make extra money with it.
When using normal mail for receiving parcels from China usually I have not to pay anything, but DHL charged me 10� for customs duties plus 20� for the "service".
I forgot to say Maggie to sent it using common mail, it is cheaper for both.
I had a similar experience when I bought my first AirSpy SDR receiver, I choose FedEx or UPS (I don't remember which one) instead of common mail expecting a safer service, but when it arrived they called me asking for a ridiculous sum for clearing the customs. I refused and made the clearance myself, not before a long discussion about charging me just for giving me the shipping documents.
So when I bought another Airspy receiver I choose mail and the parcel arrived at my door without paying any extra.
This may not apply to all countries, but it is true for Spain and even worse for other countries.
Now I (and a friend) have another toy to play with.
Regards,
Ignacio EB4APL
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El software de antivirus Avast ha analizado este correo electrónico en busca de virus.
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On Tue, Aug 18, 2020 at 08:13 AM, Dick wrote:
Can someone send me a link to the PC Control Software ?
Both links are on the wiki page
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Today DHL delivered me a couple of tinySA.
Still no powered it up, but I want to note that the packaging was really good, thanks Maggie.
The only negative comment is about DHL. DHL is a carrier and also a customs clearance agent and they make extra money with it.
When using normal mail for receiving parcels from China usually I have not to pay anything, but DHL charged me 10� for customs duties plus 20� for the "service".
I forgot to say Maggie to sent it using common mail, it is cheaper for both.
I had a similar experience when I bought my first AirSpy SDR receiver, I choose FedEx or UPS (I don't remember which one) instead of common mail expecting a safer service, but when it arrived they called me asking for a ridiculous sum for clearing the customs. I refused and made the clearance myself, not before a long discussion about charging me just for giving me the shipping documents.
So when I bought another Airspy receiver I choose mail and the parcel arrived at my door without paying any extra.
This may not apply to all countries, but it is true for Spain and even worse for other countries.
Now I (and a friend) have another toy to play with.
Regards,
Ignacio EB4APL
--
El software de antivirus Avast ha analizado este correo electrónico en busca de virus.
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DSL dropped off my TinySA yesterday. A quick check with my
Sig Gen shows it works. Now to read the manual !!
One thing I need is the PC Software. I looked at the Wiki, saw
some pictures, but I didn't see a link to the software. Perhaps
I missed something.
?
Can someone send me a link to the PC Control Software ?
Thanks, Dick, W1KSZ
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Re: TinySA: Internally generated spurious signals
On Mon, Aug 17, 2020 at 09:31 AM, Erik Kaashoek wrote:
Above 1GHz RF is like water. It flows? through every hole
? ?[Our lab called it the Dutch boy effect.? You plug one hole and RF finds another path of least resistance.
Hiding with the spur removal does not work as the spur removal removes spurs that do not actually exist but this 48MHz harmonic leakage is an actual signal.
? [There are innovative DSP solutions but I always view them as treating the symptom instead of the problem. I favor the old fashioned way of actually curing the problem by rounding off sharp clock edges so that the harmonics are severely attenuated.? some engineers favor using spread spectrum clocks that attenuate the emissions by spreading the signal power.
? The tinySA meets my needs and expectations as is.? User's with more advanced applications in mind will most likely try mitigating the MCU related emissions using their own bag of tricks.? The tinySA surface mount components damper my enthusiasm to do so.]
In a next HW revision (not planned) I will pay some extra attention to them.
[Hopefully a fellow hardware type will submit an inexpensive solution to the group in the meantime.? Source suppression seems the best route.]
- Herb
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Re: TinySA: Internally generated spurious signals
On Mon, Aug 17, 2020 at 08:31 AM, OneOfEleven wrote:
The TinySA shows a wide flat top and noise floor of only 45dB down at 12kHz away from center, where as in actual fact the carrier's noise floor is 80dB down by the time your only 1kHz away from center.
Have a look here:?
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Re: TinySA: Internally generated spurious signals
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Re: TinySA: Internally generated spurious signals
Above 1GHz RF is like water. It flows? through every hole
Hiding with the spur removal does not work as the spur removal removes spurs that do not actually exist but this 48MHz harmonic leakage is an actual signal.
In a next HW revision (not planned) I will pay some extra attention to them.
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Re: TinySA: Internally generated spurious signals
The TinySA doesn't use the ADF4350, it uses a couple of Si4432's.
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Re: TinySA: Internally generated spurious signals
Regarding ADF4351, would the Tninsa perform better with these rather than adf4350?
Steve L ? G7PSZ
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Re: TinySA: Internally generated spurious signals
Now the 64,000 dollar question.
What could be done to suppress them?
Either hide them with software tricks, such as the spur-removal option, but that might leave “holes” in the spectrum, or additional filtering/ decoupling/ screening on the board, which is out of the question for most current owners.
There is of course the human software modification - learn to live with it and adjust practice accordingly.
Out of interest, I was playing with my nanoV2 to improve screening. I found that things seemed to be worse if I applied conductive (absorption) tape inside the case and even laying the device (in FR4 unclad case) on a flat metal sheet also made things worse, especially above 2.5ghz.
Steve L. G7PSZ
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Re: TinySA: Internally generated spurious signals
Yes the unit certainly has limitations, though for the price is not to bad really.
Here's a -4dBm carrier from an ADF4351 at 50MHz.
The TinySA shows a wide flat top and noise floor of only 45dB down at 12kHz away from center, where as in actual fact the carrier's noise floor is 80dB down by the time your only 1kHz away from center.
A useful unit all the same.
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Re: TinySA: Internally generated spurious signals
On Mon, Aug 17, 2020 at 06:00 AM, hwalker wrote:
Your explanation and an illustrative screen shot deserve a Wiki entry, possibly under 'Limitations' or as an addition to the FAQ topic, "Question:?Even without anything connected I still see some signals ".
Done, The 4.8MHz is indeed present.
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Re: TinySA: Internally generated spurious signals
On Mon, Aug 17, 2020 at 03:16 AM, Erik Kaashoek wrote:
These are 48MHz harmonics generated by the MCU. For now all tinySA will show them at 48, 96, 144, 192 and 240 MHz
Erik, ? ?On my tinySA there also appears to be a sub-harmonic of the 48MHz clk at 4.8MHz.? Possibly a divide by 10 output? LOW and HIGH INPUTS terminated in 50ohm loads.  Your explanation and an illustrative screen shot deserve a Wiki entry, possibly under 'Limitations' or as an addition to the FAQ topic, " Question:?Even without anything connected I still see some signals ".Perspective buyers should know what to expect if the internally generated MCU signals will be an issue to them.- Herb
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Re: TinySA: Internally generated spurious signals
These are 48MHz harmonics generated by the MCU. For now all tinySA will show them at 48, 96, 144, 192 and 240 MHz
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TinySA: Internally generated spurious signals
Have I just been unlucky and got a bad unit, or does everyone suffer spurious signals on their TinySA?
I see specific signals at 144.20MHz, 192.15MHz, and 240.19MHz.
They are unstable, and wander over a few hundred kHz, during a period of about an hour. Each are 12-15dB above noise floor in 10kHz RBW.
They are definitely internally generated. I have applied 50Ohm loads to the SMA connectors, and even operated the device inside a Faraday cage, but still the spurious signals remain visible.
Any feedback welcome.
John
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Re: Identifying which serial port the tinySA is attached to
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Re: Identifying which serial port the tinySA is attached to
Very good.
Could the firmware not have used the unique CPU serial number to create the device ID ?
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Rachael M1AYG
Dick
