Why Tx/Rx devices are so expansives ?

Talk about other SDR products like the FunCube, HackRF, BladeRF etc.
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kelegaya
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Joined: Wed Oct 10, 2018 4:53 pm

Why Tx/Rx devices are so expansives ?

Post by kelegaya » Wed Oct 10, 2018 5:00 pm

Hello,

I was wondering why those devices are so expansives, i mean even the cheapest one are like 150€ minimum (http://www.analog.com/en/design-center/ ... b-overview).

If i ask this question, it's because cheap smartphone cost like 40€ or even below. And those smartphones are capable of Tx/Rx at GSM,3G,4G,LTE etc... So sorry, i'm a beginner, but i was thinking " Why don't they extract GSM chip of those cheap smartphone to do their usb transceiver"...
How can a constructor provides smartphones at 40€ with Tx/Rx capability and other cool stuff integrated like wifi, bluetooth, keyboard, operating system etc...

Thanks for your help :)

rtlsdrblog
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Re: Why Tx/Rx devices are so expansives ?

Post by rtlsdrblog » Wed Oct 10, 2018 8:19 pm

Smartphones are generally using a chip with does all the TX.RX functions, and normally it's a hardware radio, with no IQ output. So it can't be used as an SDR.

Kenn
Posts: 45
Joined: Fri Apr 08, 2016 8:43 pm

Re: Why Tx/Rx devices are so expansives ?

Post by Kenn » Thu Oct 11, 2018 7:30 pm

The rules of mass production I suspect. If there was a demand for SDR similar to cell phones, they'd be mass produced and the unit price would be less.

-K

rtlsdrblog
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Re: Why Tx/Rx devices are so expansives ?

Post by rtlsdrblog » Fri Oct 12, 2018 6:36 am

I assume that in the future all smartphones will be using SDR based radios. But that does use more battery and CPU power, and no guarantees that they'll be hackable into general purpose receivers.

aurgathor
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Re: Why Tx/Rx devices are so expansives ?

Post by aurgathor » Sat Oct 13, 2018 11:49 pm

rtlsdrblog wrote:
Fri Oct 12, 2018 6:36 am
I assume that in the future all smartphones will be using SDR based radios.
Disagree. Current smart phones can already do CDMA/GSM/LTE with traditional ASICs at a reasonable price, so aside from upgradeability and additional flexibility, there is not a whole lot to gain by using an SDR instead. And as you've correctly mentioned, such a phone would likely to use more power, which would be a *major* no-no.
But that does use more battery and CPU power, and no guarantees that they'll be hackable into general purpose receivers.
Hacking them to general purpose receivers would likely require both FW and HW mods, and doing the latter on phones will likely require some exceptional soldering skill.
kelegaya wrote:
Wed Oct 10, 2018 5:00 pm
So sorry, i'm a beginner, but i was thinking " Why don't they extract GSM chip of those cheap smartphone to do their usb transceiver"...
Because they contain ASICs (Application Specific Integrated Circuits) that are designed to send/receive (code/decode) GSM/CDMA/LTE/etc., and the phones cannot be easily modified to be used as general purpose transceivers. I presume that in some cases it could be possible to modify them with some kind HW mod, but those mods are not easy to do.
How can a constructor provides smartphones at 40€ with Tx/Rx capability and other cool stuff integrated like wifi, bluetooth, keyboard, operating system etc...
Because they use a handful of ICs that can be very cheap when you are making millions. In addition, I think the lowest frequency mobile phones is currently 600 MHz, (there were lower frequencies used before, but not any more) so the RF chips used in the phones don't need to go down very much. Also, handsets can be sold under cost and subsidized by carriers, so the price you see may not always reflect the true cost.

rtlsdrblog
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Re: Why Tx/Rx devices are so expansives ?

Post by rtlsdrblog » Mon Oct 15, 2018 7:31 am

I think smartphones will end up using SDR radios in the future due to cognitive radio developments, which will enable more efficient frequency sharing. That will be needed as the bands get more crowded over time. Although that's probably a good 10 years out.

Chuck
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Re: Why Tx/Rx devices are so expansives ?

Post by Chuck » Fri Oct 19, 2018 9:36 pm

Expense is a function of how many you make, and how difficult they are to make. [ Disclaimer, I work for a company that makes SDRs ]

The primary challenge is to make a printed circuit board and signal path that is very "quiet" with respect to ambient RF signals. That is why there will often be a "moat" of copper around sensitive circuits that a conductive cover is soldered to when the board is made. This prevents signals that can be in the nanovolts from being coupled to the signal paths in the circuit.. When you can keep the RF system completely inside a chip (like the RT820 does, you just need to make a quiet chip, and then the rest of the board isn't as big a problem.

Finally, there is a challenge in some of the parts, for examples filters from Atlanta Micro which are really nice and do what you want, are also really expensive! An 6 octave filter for 100Mhz to 6Ghz for example can cost $250 **per chip** and take 26 weeks to get after you order it.

So a combination of expensive parts, challenging design and manufacturing, that shows up has higher costs. But I still think the ADALM-PLUTO (which is $100 from Digikey in the US) is probably the best deal for a transceiver type SDR.

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