Help me choose an SDR/Spectrum analysi device: ADALM-PLUTO VS RF Explorer 6G WB+

[glradio]

Greetings to the entire eevblog.com community ! 

I need to purchase a simple electromagnetic spectrum analysis device for use for education purposes.

I have narrowed the list down to these devices:

Analog Device ADALM-PLUTO (about 250€) and RF Explorer 6G WB+ (440€).

I discarded bladeRF 2.0 micro xA4 even though it was my first choice, because it was too expensive, Pluto Plus Sdr because it is a clone without a known manufacturer, HackRF One because Adalm Pluto seems superior, and RF Explorer 6G COMBO+ because I do not need support of frequencies from 50 Khz to 15 Mhz.

I was thinking of buying Adalm Pluto because it is cheaper, has extensive software support, and because portability of the device is not essential and I could achieve it equally with a lightweight laptop.

What advice can you give me on this ?

[Bicurico]

You forgot to mention what you really want to do.

For spectrum analysis, the best bang per buck would be the TinySA Ultra.
Need VNA? Get a NanoVNA.
Want to write your own software to demodulate stuff and want to be able to generate signals? Adalm Pluto might be nice, I think the HackRF might be better, despite being half duplex.
I am not sure that the Adalm Pluto is still being sold?
What frequency range? Do you want to TX or just RX?
Perhaps a simple RTL2832 would be enough?
The cheapest receiver would be the RSP1 clone from AliExpress. Mind you, my first one broke after one month, second is on its way.

As you see, there are so many options, you really need to tell what exactly you want do to.

[arocholl]

It depends on what you actually want to do, RF Explorer is a calibrated measurement instrument whereas Pluto is a general purpose SDR.

[glradio]

You forgot to mention what you really want to do ...

Hello and thank you for your reply.

I knew TinySA up to 960MHz, but I didn't know that an Ultra version had come out that could go up to 6 GHz, seems also 12 GHz !)

The device serves me primarily as a spectrum analyzer: transmitting signals or receiving radio stations would be useful but secondary for my use.

The frequencies I want to receive are up to 6 GHz, in fact all the devices I mentioned in my first post go up to 6 GHz.

Do you think TinySA Ultra is superior to, for example, Pluto Plus SDR when used as a spectrum analyzer with appropriate software such as SATSAGEN to even just SDRSharp ?

[glradio]

It depends on what you actually want to do, RF Explorer is a calibrated measurement instrument whereas Pluto is a general purpose SDR.

Have you had a chance to compare the latest version of RF Explorer 6G with TinySA Ultra ?

From a quick glance it would seem that the latter's firmware options are many more and more advanced.

On the other hand, I could not say about the quality of the hardware components and reception sensitivity because I have never tried them ...

[Bicurico]

I dare to say that the TinySA Ultra beats any other affordable spectrum analyser.

The next step up would be a Siglent SSA3021X-P or a second hand professional device.

Just make sure that the specs meet your needs.

Note that any SDR based device will (normally) show a spectrum with relative values: you won't be able to measure i.e. dBm, but just dB.

While this limitation is good enough to "see" transponders of interest (to which you can then tune the SDR and try to demodulate the signal), it won't be adequate for any measurement.

On the other hand, a spectrum analyzer like the TinySA, TinySA Ultra, RF Explorer, etc., won't be able to demodulate the signal.

Again, it depends on what you really want to do.

Regards,
Vitor

[A.Z.]

just out of curiosity... why did you exclude the RedPitaya ?

https://redpitaya.com/

or maybe you didn't consider it ?

[glradio]

I dare to say that the TinySA Ultra beats any other affordable spectrum analyser.

TinySA Ultra really seems like the best choice in every way considering I don't need to demodulate the signals, thanks for suggesting it !

The next step up would be a Siglent SSA3021X-P or a second hand professional device.

The Siglent SSA3021X-P, however, is limited to 2.1 GHz.

[glradio]

just out of curiosity... why did you exclude the RedPitaya ?

The frequency range of Redpitaya devices seems to be much more limited than those mentioned in this post.

[Bicurico]

Note that RF signals above 2-3GHz start behaving like black magic.

To properly measure them, you need accessories that easily cost as much or more than your budget for the spectrum analyser itself: cables, connectors, attenuators, etc.

I would say that the TinySA Ultra can visualize and prove the existence of given signals at 6-12GHz, but you will have a huge error, attenuation and noise floor. But yes, it is amazing that you can see the signals with such a cheap device.

[ahbushnell]

This might be of interest.  Also other video's on the ADALM PLUTO.

Andy

[glradio]

I would say that the TinySA Ultra can visualize and prove the existence of given signals at 6-12GHz, but you will have a huge error, attenuation and noise floor. But yes, it is amazing that you can see the signals with such a cheap device.

I guess these limitations are also common to the other devices mentioned above ...

Verifying and visualizing the presence of a signal is sufficient and is what I am most interested in.

With the low cost of a TinySA Ultra device, it would not make sense to buy a more expensive device ...

[artag]

Also other video's on the ADALM PLUTO.

e.g. https://www.youtube.com/@jonkraft

Note that there are two versions of the Pluto. The later one can be modified for dual receive / transmit.

[glradio]

Any advice on an antenna that replacing the stock one can improve the performance of TinySA Ultra ?

A user on an official Aliexpress reseller page suggests these antennas:

Socotran SAT-771D VHF 144 430MHz
Gizont gooseneck 5g 698 MHz to 6 GHz
Taoglas TG.55.8113 617 MHz to 5.925 GHz

[Bicurico]

You cannot "improve the performance of the TinySA Ultra" using different antennas.

Different antennas will simply receive the signal in question with a higher gain, especially when the length (or equivalente characteristic) of the antenna is a multiple of the wavelength.

For frequencies above 1GHz, the antennas get shorter and shorter.

When you see an AliExpress offer of an antenna claiming a frequency range from 700MHz up to 6GHz, you can be pretty sure it is a lousy antenna!

Want a "good" antenna, take a look here: https://www.tequipment.net/Rohde-&-Schwarz/HE400/Antennas/

Best approach is to build your own antenna... Often, a simple paperclip, cut to the right length will at least be as good as those chinese antennas.

[radiolistener]

When you see an AliExpress offer of an antenna claiming a frequency range from 700MHz up to 6GHz, you can be pretty sure it is a lousy antenna!

yes, this is just a piece of wire, but it still can be used as antenna for a strong signals, for example if you don’t have a suitable rusty nail or other piece of iron in your shed 

Good resonant antenna has Q about 10 or more, it depends on your requirements for bandwidth. More wide bandwidth leads to a low Q and as result to a low sensitivity. Some short wave magnetic loop antennas have Q up to 2000 and even more, but they have very sharp resonance and very narrow bandwidth (5-10 kHz). This is how it can hear very weak signals despite the fact that it has too small size.

Antenna bandwidth, VSWR and Q-factor are all linked together, so if you increase antenna bandwidth you will lose VSWR or Q and vice versa.

Here is equations:

VSWR = (Q^2 * BW^2 + SQRT( Q^2 * BW^2 * (Q^2 * BW^2 + 4) ) + 2) / 2
or
BW = (VSWR-1) / (Q*SQRT(VSWR))

where
VSWR - worse VSWR within antenna bandwidth interval around center frequency
Q - is Q-factor
BW - is bandwidth relative to a center frequency: BW = bandwidth_in_Hz / center_frequency_Hz


In short, good resonant antenna works as a bandpass filter. It cut-off unwanted frequencies and it allows to get signal-to-noise gain because noise floor drops down. More low bandwidth leads to more noise cut-off and better noise floor, better sensitivity. But if antenna is wide bandwidth it will pass more noise power on it's output and you will have very high noise floor and as result low signal-to-noise ratio and low sensitivity.


Regarding to the original question, I'm not sure if RF Explorer 6G COMBO+ can work as SDR, but at a glance it is marketed as a usual spectrum analyzer. Why do you think that it can work as SDR? There is even no mention about SDR on its site...

If we compare  ADALM-PLUTO with HackRF, then ADALM-PLUTO is obviously better, because it has better dynamic range.

[glradio]

Regarding to the original question, I'm not sure if RF Explorer 6G COMBO+ can work as SDR, but at a glance it is marketed as a usual spectrum analyzer. Why do you think that it can work as SDR? There is even no mention about SDR on its site...

It was an inaccuracy in my initial post: now I have modified the title.

Have you had a chance to compare TinySA Ultra with the other devices in my post, when used as a spectrum analyzer ?

[radiolistener]

I don't have tinySA, so I cannot evaluate it's ability. At a glance tinySA is more convenient for mobile usage. But if you have PC, ADALM-PLUTO will be more flexible and can provide fast realtime spectrum analysis with better dynamic range.

[glradio]

... But if you have PC, ADALM-PLUTO will be more flexible and can provide fast realtime spectrum analysis with better dynamic range.

Many people here suggest Adalm-Pluto: has anyone had a chance to try this clone ?

It's an advanced version of the original that removes one of its main limitations by adding a gigabit ethernet interface interface.

[radiolistener]

Many people here suggest Adalm-Pluto: has anyone had a chance to try this clone ?

I wanted to buy it, but unfortunately I have no ability due to war.
At a glance it looks good, but since almost all Chinese devices have some pitfalls, this one also can have it's own pros and cons...

[glradio]

At a glance it looks good, but since almost all Chinese devices have some pitfalls, this one also can have it's own pros and cons...

These are the enhancements of Pluto+ over the original version

[Bicurico]

Note that these enhancements are on HW. You would need to develop your own software to benefit from them, if I am not mistaken.

[glradio]

Note that these enhancements are on HW. You would need to develop your own software to benefit from them, if I am not mistaken.

There is probably a custom firmware that needs to be loaded by acting on the pcb jumpers, as this part of the video would suggest

[glradio]

Concerning the standard version of Analog Device ADALM-PLUTO, I read from several sources that the real big limitation of this device is the Usb 2.0 interface that prevents to take advantage of the 20 MHz bandwidth of the device (limitation that would be even more evident by unlocking the device to bring it to 6000 MHz and 56 MHz bandwidth).

Does anyone who has tested the device know if these claims are true or just exaggerations ?

[Bicurico]

I own both the Pluto and the HackRF One. I somehow prefer to use the HackRF One. Even for SDR it produces better results.

And yes, USB-2.0 is a limitation on the Pluto. That is why I am of the opinion that the Pluto is great for hackers who are able to program for it. If you transfer the FFT to the CPU running inside the Pluto, then the USB bandwidth would be more than enough to output the sampled sweep data.

But again, for under 200 Euro just get the TinySA Ultra for spectrum analysis and buy an RTL 2832 dongle for demodulation.

[glradio]

I own both the Pluto and the HackRF One. I somehow prefer to use the HackRF One. Even for SDR it produces better results.

In some comments I read that HackRF is a 2.4 GHz Sdr with the addition of a mixer for frequencies beyond that threshold, and this significantly reduces its sensitivity beyond 2.4 GHz, while Adalm Pluto is a single stage mixer design without this limitation ...

But again, for under 200 Euro just get the TinySA Ultra for spectrum analysis and buy an RTL 2832 dongle for demodulation.

I am ordering it today or tomorrow from the factory store on Aliexpress recommended on the official Tiny SA Ultra website, but I am considering getting Adalm Pluto as well ...

[RoGeorge]

Don't know the other platform, only have a Pluto (it was about $70 back then).  Beware that Pluto does not have any filters on the input (or output).  The Tx is almost square wave, which will put a lot of harmonics.  This might be useful if you want to use odd harmonics, can generate as well 18GHz or more. 

Also, Pluto doesn't make use of the second channel (the chip can have 2 Tx and 2 Rx channels, Pluto can acces only one Tx and 1 Rx.  Another thing not obvious in the datasheet is that the Tx and Rx oscillators can not be synchronized, which make impossible to built a VNA based on Pluto.

Local oscillator is pretty sensitive.  Can "feel" if you wave your hand near it, at 10-30cm (capacitive coupling, Pluto has no shielding).  It can feel if you blow air on it (temperature change).  Buy something shielded, this is a must. 

Good thing is that it can be unlocked for 40MHz-6GHz, or so, but that is a hack.  It works, but the results might not be as in the datasheet.

Pluto is great for what it was destined, an educational board.  For real life usage, might be unfitted or too expensive.  Another thing, being a programmable and open source project was very tempted at first.  Though, I've never tryed to modify anything in the FPGA part (I was already familiar with Xilinx, Zynq and Linux, but the project is big and hard to grasp, not easy to modify, and the FPGA is almost full anyway, so you can not add much extra).

At $200-300, as a Pluto costs now, you are already in the range of second hand spectrum analyzers, or portable VNAs (the ones for radio towers, not the nanoVNA kind).

If it's for didactic purposes only, might worth buying cheap AliExpress modules, and cobble your own SDR/SA.  That will give a lot of learning.  SDR basics can be grasped in audio, with only a soundcard and a PC, in case you want to keep the cost zero.

[glradio]

Now waiting for TinySa Ultra to arrive ...

Thanks to Bicurico for the precious suggestion 

[DaneLaw]

Also got myself an HackRF some years back, and its one of the RF tools I use the most, but mostly just fiddling with RF and trying to wrap my head around it while getting familiar with signals in everyday things, and hopefully learn as I go.
As a newcomer with no real specific purpose other than learning a little alongside a fascination of gadgets, not least devices that can give a little insight, I went with these relatively cheap synth chip-based CN spectrum explorers.
# MAX2870 based PC-spectrum in a casing seems to manage from 22MHz to 6.55Ghz. (100US)  https://tinyurl.com/fd6bstte
# ADF4351 based PC spectrum (just the board that I fitted into a casing) (20US) // though MAX2870 chip way preferred IMO-
# HackRF+Por3.2 (CL) MAX2870? with incl. battery and a handful of antennas (150US) and I then fitted an int speaker.  https://tinyurl.com/2p85pbmb / https://tinyurl.com/app9hxtt
Its RF limit peaks somewhere between 6.6Ghz and 7Ghz, though frequency response/sensitivity/RF output varies greatly across the span on these CN budget RF synth chip-based devices, took an RF measurement around 2.45Ghz and got around 24.5mW output on HackRF, but its an old cheap PC-based USB3 RF power meter from CN to like 30 US bucks that goes from 0 to 12.000 MhHz (if I recall) or something clueless big frequency-span like that, so take that value with a pinch of salt, though down in sub-GHz its a few mW higher.
I know that HackRF as a Half Duplex device does seem to claim 25mW output (alongside you can toggle DC load) but I doubt it can manage 25mW up around 2.45Ghz  but Im not sure of the HackRF output power across it span and where on the span, it will perform 25mW.
https://tinyurl.com/y7ekzc6v

Picture slide https://tinyurl.com/3s3c7ym4
4GHz HackRF as signal source.

 
AIO FPV cam 5.8GHz

cheap 5-dollar log antennas from China, but the frequency response/sensitivity varies obviously greatly across the span on these CN budget RF devices.

and you can also use the HackRF with Android tablets or mobiles or your car's Android-supported entertainment screen.
5.8GHz analog FPV cam. (FPV for multirotor)

[DaleWentz]

I have a few too many spectrum analyzers, An HP, A Tektronix, A new siglent, the tiny SA and now the Tiny SA Ultra. I also have a bunch of SDR's. There is a lot to be said for the Tiny Ultra. Its portable self contained and has proven to be as accurate as my needs be most of the time, especially away from the bench. My only complaint with the Tiny SA was the little screen, but the Ultras screen is almost as big as my HP's display. Perfectly usable size for most work.

[glradio]

Also got myself an HackRF some years back ...

Any experience with TinySA Ultra ?

I have a few too many spectrum analyzers, An HP, A Tektronix, A new siglent, the tiny SA and now the Tiny SA Ultra ...

How does your equipment compare to TinySA Ultra in terms of performance, accuracy ?

[DaneLaw]

Also got myself an HackRF some years back ...

Any experience with TinySA Ultra ?

No not the Ultra, I did purchase a TinySA Ultra about a month back, on Aliexpress alongside a cheap TinySA clone from another store (Meterk, model below), but the seller with the Ultra, won't ship, and just posted a fake inactive tracking, so Im in limbo until the Aliexpress system, takes notice and money are returned, and will then look for another source.
Got no actual reason' why he won't ship, says something about customs-production-problems, which makes no sense.. either the lying excuse is that "it was returned back from customs" or its "productions problems" but weirdly enough he won't remove his listings, and I can see he sold like 9 after I made my purchase, so stay clear of this rancid store. https://www.aliexpress.com/item/1005005241119145.html?

Either, it's because it's simply not profitable for him to ship to the price I was able to get it for at AliE-sale. (incl VAT 130US) https://tinyurl.com/5yt7kdnx
or maybe it's because I asked him if he, were familiar if there are different models of the "TinySA Ultra".. - (I was fishing to sense if there is a clone of the Ultra on the CN market yet, but no reply).
The other TinySA (clone) which vere labeled to be EU stock, was delivered in like a week (40 US incl 25% VAT & shipping)
so just been fooling around with that, but it defeats the purpose when only the misfit arrived.

[RoGeorge]

until the Aliexpress system, takes notice and money are returned

From what I know you'll have to open a dispute, or else Aliexpress will assume a successful transaction.

[DaneLaw]

until the Aliexpress system, takes notice and money are returned

From what I know you'll have to open a dispute, or else Aliexpress will assume a successful transaction.

Yep, though the dispute system is often locked down' until a certain weeks/months has arrived but this approach of inactive fake trackings, ix such a problem that Aliexpress will close them if a tracking number is fake/inactive.

The use of fake tracking, is sadly very common on Aliexpress if the seller doesn't wanna ship, - they do it because the system will hurt their store "if they don't ship an item that somebody has purchased and the time for shipment just summons", - it's less hurtful for their store, to just put a fake tracking, and then ask the buyer to fx dispute, but Aliexpress are familiar with that tactic, & will close the order with this notice below (screen dump), and I believe that also hurts the seller.
When I purchased the TinySA Ultra, I also purchased a touch-based signal generator with "MAX2870" as I really like that synth-chip, but sadly that seller, was also hollow' and decided to put in a fake inactive tracking, and that "order" just been handled as you can see below

Many stores on Aliexpress, will offer a product, and then after you have purchased it, the seller will analyze if it makes sense to honor that purchase - and often they won't, and instead try desperately to get you to cancel the order with the direction "you have changed your mind and don't wont it anymore" as it won't hurt their store.
Here you can see the notice Aliexpress gives when the Aliepress system, notices these fake trackings, - and this is just a few days ago - since Aliexpress closed this fake tracking.
but all this hassle, - is sadly Aliexpress in a nutshell and something you have to deal with when using that Chinese platform. https://tinyurl.com/5t49pduv

[glradio]

... stay clear of this rancid store ...

Pay attention when purchasing the TinySA Ultra device. As specified on the official website, there are many unofficial clones around, and the only way to get the original device is to buy from a seller on this list.

In general, I always buy only from sellers who have sold the most products and obtained high satisfaction ratings from buyers.

In the case of the store you listed, however, I see that for the product you purchased, it does not indicate the total number of pieces sold and there is no user feedback.

Zeenko Store on the other hand has sold over a thousand pieces of the TinySA Ultra and received only positive reviews, many of which seem to be given by industry professionals who have compared the device with their professional spectrum analyzers.

[DaneLaw]

... stay clear of this rancid store ...

Pay attention when purchasing the TinySA Ultra device. As specified on the official website, there are many unofficial clones around, and the only way to get the original device is to buy from a seller on this list.

In general, I always buy only from sellers who have sold the most products and obtained high satisfaction ratings from buyers.

In the case of the store you listed, however, I see that for the product you purchased, it does not indicate the total number of pieces sold and there is no user feedback.

Zeenko Store on the other hand has sold over a thousand pieces of the TinySA Ultra and received only positive reviews, many of which seem to be given by industry professionals who have compared the device with their professional spectrum analyzers.

We already debated that in the other thread about the "Ultra"..
You can take a look there for further details - if you are unsure what is up or down..just search for "TinySA Ultra" above in the search bar.
// https://www.eevblog.com/forum/testgear/tinysa-ultra-launched/

Numerous clones on the "TinySA" nothing new there, it's been like that for years, they are around half in price, - but so'far no proof of any clones on the "Ultra" according to Erik some weeks back, and why I wrote above.. "fishing to sense if there were multiple variants of the Ultra" - but sofar it still looks like all the TinySA "Ultra" on Aliexpress are still legit ones, likely all produced by Hugen or.. - I haven't seen signs of TinySA Ultra clones "yet".
- In general, take Aliexpress stats with a pinch of salt..be careful blindly trust these sale statistics alone, they can be manipulated.. the above store manually removed his stats after I asked about why he kept selling, if he couldnt deliver, as I could see the sale-number elevate, - he then removed the sale stats.

Many of these site-stats can be manipulated to suit the sellers narrative in one way or the other, even on Amazon where it even looks like they can change product midway on a given listing' so take them with a pinch of salt on wholesale sites' like Aliexpress or Amazon.