shushi_boi

Summary
Is this schematics accurate so far? What type of connectors and antennas should I use for this to work?
Summary: Is this schematics accurate so far? What type of connectors and antennas should I use for this to work?

From following this project (PiTxSDR)

and after watching this presentation (the RadioInstigator which builds on the previous project),

I was interested in building a RadioInstigator for a raspberry project that I want to build, but I had a few questions in regards to the parts and radio hardware that was used in this project. Down below is a quote from the author of the project which he lists all of the parts he used and bought,

This is a list of materials you will need to complete this tablet.

Please be aware, that since the product links are to a variety of auction sites, these prices **WILL** change. I also considered a few things as 0 cost. For example, USB cables are ubiquitious. We cut a few up.

I also have a large format 3d printer. You probably don't. I didn't include cost for printables, or nuts and bolts. I buy in quantity from Fastenal or McMaster Carr.

Total cost tally as of 17 Feb 2019: $157.50 -- 3d Printables -- 0. The printables. I have my own printer. You need a full printable size of 200mm x 200mm to print these parts -- Electronics -- 1. Raspberry Pi 3 B+$36.00

2. MicroSD card (salvaged from other projects) $0 3. PWRbar 10AH battery (purchased from Office Depot on sale)$5

4. LCD Touchscreen $58.00 5. RTL-SDR$9.50

6. IS11-BT05 Bluetooth keyboard $20 7. Random USB wifi that Kali linux liked, junked find 0$

8. (OPTIONAL) CrazyRadio , allows easy keyboard mouse sniffing/injection for wide variety of hardware $8 9. (OPTIONAL) (WARNING) GPS chip , bought on AliExpress for$10 but cannot find anywhere. Dealer no longer is there.

-- Cables --

10. MCX to SMA adapter $4 11. SMA female to jumper lead$2

12. 50cm HDMI ribbon $8 13. Pile of "donor" micro USB cables$0

14. SPST Switch. 11mm diameter. Radio Shack deal. $1 -- Antennas -- 15. Really long wifi antenna found with above usb device 0$

16. 2 Antennas 50MHz-1200MHz $20 Ebay store closed... :/ I need a reliable source. This will likely balloon the budget. 17. (OPTIONAL) Log Peroidic Antenna$9.20

-- Screws/Nuts --

18. M3X45 cap screws (X4)

19. M3 nut (x4)

20. M3X16 cap screws (X6)

21. M3 Heat set inserts, 4.3mm tall (X4)
NOTE: If you redesign the back cover for M3 nuts, you can use them instead. It won't look as finished, but will certainly work.
Although he lists most of the parts, there is some ambiguity on some parts, so I'll post a few links to some of the possible options that I found (for those interested also in this project),

1.)GPS
GPS Dead Reckoning Board - NEO-M8U (GNSS)

or
Adafruit Ultimate GPS Breakout - 66 channel w/10 Hz updates - Version 3

or
SparkFun GPS Breakout - ZOE-M8Q (Qwiic) (compatible with a Raspberry Pi, but no examples of code for using it directly connected to a Pi so you would need to write your own code)

2.) Power Supply
Renogy 72000mAh Laptop Power Bank

Krisdonia 50000mAh Laptop Power Bank

MAXOAK Laptop Power Bank 185Wh/50000mAh(Max.130W) Portable Laptop Charger

iMuto Portable Charger 30000mAh

ROMOSS 30000mAh 18W Fast Charge

3.) WIFI USB Dongle
KuWFi Dual Band Bluetooth 4.1 WiFi USB Adapter, Wireless AC 1200Mbps 5GHz WiFi USB 3.0 LAN Adapter High Gain Antenna Network Card for Windows Linux Systems

Lemorele Wireless USB WiFi Adapter Bluetooth 4.2 5G/2.5G Dual Band Wireless Adapter AC 600Mbps Mini WiFi Dongle

based on these parts and the ones I added, I'm still not sure what characteristics or qualities I should look for on the two antennas the author mentioned but could no longer find any other listings from the same ones or the seller. So my first question would be where could I find SMA type connector antennas like the one the author used for this project? And do these antennas have to be only receivers or also capable of transmitting (transceivers)?

I tried to create a simple schematics of the project, which I'll attach right here,

As shown in the schematic diagram, I've used a green question mark "?" to indicate the areas that I am confused on, although I'm not completely sure on how well I created the schematics, which I used this image from the author, as well as looking up what each pin were for the Raspberry Pi 3 and from parts he included in his purchase listing,

My second question is about the wires that connect the dongles to the antennas, as well as the type of connectors the RTL-SDR, and CrazyRadio have. Based on this reference image, it seems that the SMA Female Nut Bulkhead to MCX Male Straight RG316 cable, has it's SMA Female (jack) connector end connected to the SMA Male (plug) ends of the two antennas (which are the ones from the first question that I mentioned that I'm looking for), but attempting to look for some sort of datasheets for the RTL-SDR and the CrazyRadio dongles, to verify that they are MCX Female connectors which seems to be the case from the above reference image from the author, I had no luck finding that information for the RTL-SDR dongle other than the aliexpress page which has limited information in that regard, Aliexpress link for the RTL-SDR device, but I did find what seems to be a datasheet to that CrazyRadio device or a related one here,CrazyRadio datasheet PDF, which on the bottom of page 2, under radio specifications, I believe it says that the connector for the CrazyRadio dongle isn't MCX female, but actually a RPSMA connector (I'm assuming a female). Is this correct? and would the SMA Female Nut Bulkhead to MCX Male Straight RG316 cable that the author recommends be the right cable for these dongles?

I'm sorry for the long post, but I hope that I covered everything that I possibly could and included as much information about this as possible if someone else was also interested in creating one of these devices.

Most information from this project could be found in the author's Gitlab page, which also includes the code and all other relevant information about this project,

Last edited by a moderator:

Mentor

berkeman

Mentor
I can't tell after just skimming the above, but what in what bands (and with what powers) will this thing be transmitting? If all the radios are in receive only (for listening), it should be okay. But if you will be transmitting in any bands, you need to be sure to keep the power and harmonic content down and legal. Plus, unless you know what you are doing, whenever you transmit with one of those closely spaced radios, it will likely desense all of the other receivers...

shushi_boi

Nice find! I wasn't aware of that article until now, but I only learned of this project through the previous PiTxSDR where someone had reference to this newer project since the author of the first project hasn't been working on the PiTxSDR.

shushi_boi

I can't tell after just skimming the above, but what in what bands (and with what powers) will this thing be transmitting? If all the radios are in receive only (for listening), it should be okay. But if you will be transmitting in any bands, you need to be sure to keep the power and harmonic content down and legal. Plus, unless you know what you are doing, whenever you transmit with one of those closely spaced radios, it will likely desense all of the other receivers...
Thank you for your informative response and important caveats! I was thinking about this point more prfoundly, on whether I only want to receive signals or also transmit, but because I had originally planned on including an FM-AM radio receiver (especially important distress signals), VHF maritime radio receiver, as well as GPS, as well as some transmitter devices that are able to communicate with your television for example, or allows you to transmit distress signals. Having looked for raspberry pi projects that included these elements, I found that the PiTxSDR included all of these bands which would allow me to compress all of these objectives and features and costs to just a few antennas dongles and the pi itself, which would allow me to also learn more about radio signals and frequencies, which I read is important for an individual to get a license and get some training as well which it doesn't seem to be that expensive to do.

But to answer your question, I'm not at all too sure yet since the author doesn't seem to mention those things in great detail, most of the information relating to this I believe is in the second video that I linked to as well as the Powerpoint file that's included in his Github page.

https://gitlab.com/crankylinuxuser/siginttablet/commit/5e84314bf0198c9d3e9cb90a9f589d5095a4931a

Last edited:

berkeman

Mentor
which would allow me to also learn more about radio signals and frequencies, which I read is important for an individual to get a license and get some training as well which it doesn't seem to be that expensive to do.
Yes, it is pretty inexpensive to get your HAM radio license and start learning more about radios. Plus, there are lots of HAM radio clubs with members who are happy to help you learn. Go to the ARRL website that I link to in my footer, and do a search for Clubs and license exams in your area. The club folks will be happy to let you know your various options for learning the basics so that you can pass your exam, and get you started learning about all sorts of radio stuff.

www.arrl.org

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