(Part 2) Top products from r/RTLSDR

Mine was sold with an antenna, but there's other inmarsat traffic to poke at after Outernet moves. :)

I like the $49 price point, that's sort of a psychological magic spot. Under $50 for a board that's similar to any of the $30-40-ish embedded boards plus a $20 rtlsdr plus a $5 USB hub all built in? Yeah, that's pretty sweet. Somebody's gonna pair that sucker with a PoE splitter and put it tower-top.

Okay, so here's my logic: Let's assume a single SKU doesn't make sense long-term. You want to get the cost down on the 256MB, Outernet-specific version. So make that one. What's the most sensible configuration for the other(s)? Can just one additional SKU bring broader appeal?

I feel like making the 512MB version with 1090-specific RF parts might be the best route for general-purpose functionality. It still has the bypass path for "everyone else", the ADS-B market seems pretty active, and it would seem to minimize module count and soldering for the largest number of users. I never even looked to see if the bypass path also has bias-tee functionality, but that would be good.

And for those of us who want to build our own filters right into the thing, since we're comfortable with soldering already by definition, we can always scrape off the 1090 parts and reuse the pads. :)

The only folks left out in the cold by that split would be those who want to do L-band stuff but need the big RAM. Which is definitely a few people -- but I think most of 'em already have a Dreamcatcher, probably? Or just do another run of those and set 'em up as a while-supplies-last third SKU. Which may have been what just happened with the clearance sale. They had their chance!

Could (all) the alternate version(s) be offloaded to rtl-sdr.com or someone? So the only one you'd be on the hook for supporting would be the "official" Skylark-specific board, and everything else is for experimenters, here's a schematic, here's the radionerds page, figure the rest out.

See above. Are you in the US?

For what your goals, I suggest you read the ARRL license guides. While they follow the syllabus of the question pool, they provide a high-level treatment of the background. It doesn't go into great depth but it covers a lot of tops. They are several hundred pages each. Unfortunately they are a little more expensive than they should be -- they include a CDROM (what year is this?).

The question pools change every four years. So make sure you get the current versions.

For the US there are 3 license classes, 1) technician, 2) general, and 3) extra class.

You might find some of the technician information fairly basic, it's the intro license. But you'll find at least starter radio theory. By the time you are done with Technician and General you'll have a pretty good overview of a lot of radio concepts. SDR and other things will start to make more sense. Depending on your interests, the extra class manual might cover too much detail and esoterica.

• Technician Class - https://www.amazon.com/ARRL-Ham-Radio-License-Manual-ebook/dp/B00OZ12X14/
  
• General Class - https://www.amazon.com/General-Class-License-Manual-Amateur/dp/1625950306
  
• Extra Class - https://www.amazon.com/ARRL-Extra-Class-License-Manual-ebook/dp/B01FTDEJN6/
  
  If you aren't in the US find the material for your country.
  
  There is a lot of stuff freely available online, but almost all of it is just going to teach the question pools and probably take more time to learn what you want to learn

The #1 thing that improves antenna performance is more surface/volume area of antenna elements. Why? Because you are intercepting a 3-dimensionally propagated EM wave and the larger the area, the more energy of the EM wave will be collected and appear at the terminals of the radio you attach it to.

The active antennas are simply amplifiers. If you have nothing to amplify it won't do much good: garbage-in-garbage-out, or more accurately, noise-in-noise-out.

For VLF and LF you can get by OK with a "ferrite loop" antenna because of the magnetic coupling advantages of those frequencies and such loops. For HF, not so much. Better is ANY long wire antenna (basically any length of wire hung at least 10 feet above the earth).

If you have restrictions on where you can put an antenna, even putting a wire in the corner of ceiling and wall is often enough to significantly improve reception. This article is good for that as is the ARRL book "Antennas for Small Spaces. The first link goes into gory detail about "lengths", "tuning" and "loading" but strictly these are primarily required for transmitting but even with "mismatching", you usually get better results than active antenna or no or short antenna.

LNAs are only good if you have decent signal coming in from the antenna first. Again, noise-in-noise-out. You can't magically overcome noise or pull-in a signal that isn't there in the first place (i.e. is below the thermal noise floor).

> I read 3/8 inch wire is optimal, does it matter if it is solid or stranded?

Doesn't particularly matter, the wider the conductor is relative to the target wavelength you will get some more broadbanded response from the antenna (warning this is a generalization) but other than that it won't affect anything. I'd use 3/8 copper plumbing over 3/8 wire if I had to go with that gauge. #14 speaker wire and tape measures are what I primarily use for antennas.

Stranded is better if it is exposed to high winds and isn't rigidly tied to a structure as it won't work-harden as fast, but this applies to HF wire antennas more than VHF antennas. At 3/8 you shouldn't worry either way.

> The wire I have is aluminum, is there a significant difference aluminum and copper?

Aluminum wire is an absolute bitch to solder if you are unfamiliar with soldering. You need lots of heat. The alternative is crimping (buttsplices or other automotive connector) which is a better idea but if you're doing a QFH it might be a tad cramped inside the conduit (if you're building out of conduit).

Be aware of galvanic corrosion if you're crimping/soldering aluminum and copper together, especially if its exposed to the elements.

> What kind of termination do you use for your antennas? My RTL-SDR uses an SMA but I will be purchasing an adapter for BNC because I have another antenna with that connection.

For receiving antennas I like F type to SMA so I can use lovely cheap and low-loss RG6. If I'm going with a transmitting antenna I prefer BNC or PL-259 (which is a bad connector but its easy to assemble).

What you mean by ground? I have heard the term but not sure how it applies in this case. I used this wire https://www.amazon.com/gp/product/B000HACYOS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 (may or may not make a difference on the type but this is really cheap and seems really good quality). I connected one end to the telescopic antenna (with alligator clips) and strung it in between two branches of a really big tree near the house by simply wrapping the wire around something you can throw high enough to get through the space in the branches and then I took the wire over a seat that is attached like a swing (this is near the tree) and then took the wire back over the swing and then wrapped the excess around the wooden part of the swing (side of the swing wooden part). The entire wire goes from the back port to the tree pretty high up and onto the swing without touching the ground. I also wrapped it on a spot of the backporch so the wire would go from the backporch to the tree high enough were it should not interfere with someone walking under it or grass cutting to prevent needing it to be moved often.

Honestly, just get a powered HDTV antenna with VHF rabbit ears. I randomly tried plugging my TV antenna into my HackRF and it gets exceptionally great signal, especially compared to the ANT500. This one is powered too, which causes interferance on the lower end, but it has an on/off switch.
This also works great in the 2.4 -5 ghz range I've found.
https://www.amazon.com/Omnidirectional-smartpass-Amplifier-Freeview-Channels/dp/B07VT3TBHY/ref=sr_1_3?keywords=tv+antenna+vhf&qid=1570897323&sr=8-3

Get a USB extension cord, should help massively if you can put it next to a window instead of the middle of an apartment.

The active ones are best https://www.amazon.co.uk/UGREEN-Extension-Amplification-Keyboards-loudspeakers/dp/B00B2HP3A2/ref=pd_lpo_vtph_147_bs_t_2?_encoding=UTF8&psc=1&refRID=7QJ9JTHT6ERB4H99WFHR

I just got a ZDA 1.7/2.1 antenna and it worked out fine. It doesn't have a secondary reflector, but I was able to get vit averages down to ~450, with it sitting on patio furniture. Hopefully I can get it lower with a proper mount next weekend. I may also attempt a DIY secondary reflector.

https://www.amazon.com/1710-2170-Grid-Parabolic-Dish-Antenna/dp/B07DQS39RZ

I had it out receiving for about 7 hours and didn't have too many dropped packets, but my elevation is 45 degrees and pretty forgiving I imagine.

Note that I had this particular seller cancel my order 2 times. I just kept placing the order until they finally gave in and shipped it to me.

Something like this?.... Interesting idea. Thanks!

Yes, the Himawari-8 data is part of the data that's relayed from GOES-16. This is also why I'm able to capture some GOES-15 data too (which my antenna wasn't pointed at). If you look at the "Readme" in the text directory, you can see the types of data being broadcast (the NWS/NHC stuff is pretty interesting, too)

As for my antenna, I'm using this 1.9ghz parabolic grid antenna.

Yeah don't use those to split signals. Get a regular 2 way splitter. I've used the cheap walmart/wherever kind, but found these work pretty good and the frequency range is a lot higher and lower. https://www.amazon.com/DirecTv-MSPLIT2R1-Approved-Zinwell-Splitter/dp/B003H2HNQW/

Looks like I need to look into that adapter it’s a single unit one (link). I may order a new one or different brand. In the mean time I’ll try to clean out the connector with alcohol and see if that helps.

Sure.The dish is an old unbranded one we got for free, it seems to be a simple offset feed. I could take a wider photo of it, but seems to be nothing special or of note.
The GPS antenna is one I pulled out of an old broken GPS system. It is just the patch antenna, it does not have a low pass filter or amplifier on it at all. (This is not the one, but probably pretty close; https://www.amazon.com/gp/offer-listing/B00R3PFMRG ).
The LNA is one I got off Amazon in the USA. It's probably not that great, but seems to help a lot, looking forward to getting the Sawbird IO ( https://www.amazon.com/gp/product/B07K1NMC23 ) today and will make a note of any difference in the signal strength.
It is powered over the line by a bias T, so we use the SmaTee ( https://www.amazon.com/gp/product/B06Y1D7P48 ) to provide the 5v it requires.
I did not want that 5v to get into the AirspyMini, so I got one of these splitters;https://www.amazon.com/gp/product/B003H2HNQWIf you take a look at the product image, you can see that only one leg passes DC, the other leg is blocked.
If you have any more questions, just ask!

OS is Raspian; Documentation can be found all over the place for installing.

Software used for tracking trunks in the Baltimore Co MD, Carroll Co MD, York PA area is called OP25

Method of configuration that I used can be found here (Big shout out to Johns tech blog) This guide is amazing.

https://www.hagensieker.com/wordpress/2018/07/17/op25-for-dummies/

8 Inch monitor can be found here https://www.amazon.com/gp/product/B07FP2F9XY/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

The antenna used can be found here in which I retrofitted with a camera tripod

https://www.amazon.com/gp/product/B075QCJM6S/ref=ppx_yo_dt_b_asin_title_o03_s01?ie=UTF8&psc=1

rtl-sdr dongle used can be found here

https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2/ref=sr_1_2_sspa?crid=3RE7FZK09J0QX&keywords=rtl-sdr.com&qid=1558445253&s=electronics&sprefix=rtl-sdr%2Celectronics%2C124&sr=1-2-spons&psc=1

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The case that I am using for this Raspberry Pi B+ can be found here

https://www.amazon.com/gp/product/B07G1LMFRG/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

The speaker that I wound up using and not in this pic is an Anker Soundcore boost, but I also use headphones when I take this to the office.

All radio system-specific information can be found at radioreference.com.

Getting the true control channel can be challenging sometimes as the db on radio reference is not always correct, at least for my area. Also, trial an error I was able to determine that the offset for my dongles is -1.

You need to get a Grid Antenna like this (I bought the last one :P) and you'll also need an LNA, preferably, this LNA/Filter hybrid from NooElec.

You will also need an N type male to SMA male (depending on the antenna) if you were to get one like mine.

And yes, you do need an LNA for this. Don't be like me, thinking I could do it without one, had to wait another two days for one :P

After that, i'd recommend you get a stand for the antenna to be mounted on, like a modded tripod. I use an old umbrella stand (super bottom heavy) and a wooden stick from a broken broom.

Thanks Everyone, I went ahead and just bought 2 new RTLSDR (https://www.amazon.com/gp/product/B00VZ1AWQA/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) and some adapters for now (https://www.amazon.com/gp/product/B00RF15070/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1) Im hoping to use unitrunker with the 2 dongles and then eventually make an antenna to get NOAA Images

The ARRL Handbook.

Here's an Amazon link: http://www.amazon.com/ARRL-Handbook-Radio-Communictions-Communications/dp/1625950195

Although you may be able to borrow a copy from your friend Torrence. ;)

Pretty cool. What’s the monitor?

Edit: found it

I pulled these images using a IEIK SDRMCX RTL-SDR, RF coaxial coax cable F female to MCX, and some Rabbit Ears I got off eBay. I live right by a school. So during the day I just went down with my laptop and sat on the ground and held the antenna above my head. My next thing is to build a QHF antenna and set it up outside and have it pull images all day. If anyone has a goo guide to do so or have any ideas please share.

Would this be any good?

Sounds like you need one of these kits

This is pretty dope.

Have you had any issues with the speaker-mic connection?
I know my UV5R is a bit finicky when it comes to that kind of hookup.

I ended up going with an 'official' APRS cable: https://www.amazon.com/gp/product/B01LMIBAZW/
and a breakout mic/headphone splitter.

I've been able to capture a few amateur satellites, but I've never tried the NOAA sats.

Any caveats to this versus the raw digital data over the SDR?

Yes but this problem was not pointed out in your article that is showing a 0,50$ rotary encoder; the next effort is to find a cheap solution with an encoder with no detents. For the optical encoder in the link, it cost more than buying a PowerMate

The cheapest optical encoder i could find is this one but the minimum power supply is 5VDC and i don't know if it can be powered directly from the USB as i want to connect it to a mouse to replace the scroll wheel encoder.

Just buy this: https://www.amazon.com/BTECH-APRS-K1-Interface-APRSDroid-Compatible/dp/B01LMIBAZW

Then you can pipe audio out to your PC and also do APRS on your phone (aprsdroid).

Also be aware that you need an audio in on your PC that is either the single jack for mic/headset or an adapter. Google a bit on the differences in audio jacks of that sort, you'll understand what I mean.

For the less than $20 it costs, it beats fkn around with half-assed cables that wear out really quick and might damage your radio / pc.

You could kind of use it like a SDR, in that you might be able to use it as bandscope, I don't really know, I use an RTL-SDR (same cost or less then what you paid for your radio and I recommend getting one because..) for things that require unfiltered audio (what would be called an IF Tap if you were using a hardware radio).

And people will jump on this and say you can tap your Baofeng too, which you can, but for as cheap as this stuff goes for, it makes more sense to buy it instead of tearing up your radio and making janky Frankenstein cables.

And the cable with the USB is just a serial to USB converter, it's only good for programming. There's no DAC/ADC for audio.

Keep it simple.

I have the same SDR dongle listed in your post. I bought it just under a year ago on an impulse and played around with it for 3ish months (set up an antenna in the attic, bought an LNA, etc.) I mainly use it for FM radio now. The antenna(s) you have for tv/radio should work with the SDR dongle if you get one of these.


As for software, I mainly use SDR# (download).

i chose to go with the one from rtl-sdr.com is only $15 and is in a metal case to further cut noise. most are exposed pcb. I would get the fm trap filter before worrying about antennas. I went the other route. upgrading antenna first and it's just noisier, since it can better pick up the FM signals. one last tip. get an active usb extension. this allows you to move the radio away from the electrically noisy computer. a longer usb cable trumps a longer antenna lead. you don't lose signal from a longer USB.

this one worked perfectly, so long as it was attached to a higher powered USB port. ones that cannot supply the juice make the radio drop out as soon as you turn it on. https://www.amazon.com/gp/product/B00B2HP3A2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I have been curios why no one make a dongle using the same components but with an selectable FM trap and LNA built in. Neither takes many components.

btw, an LNA ( low noise amp) is also a great addon. as is an upconverter. I have a spyverter on order.

RTL-SDR Blog sells a pack of adapters that will allow you to use a variety of cables with the MCX connector on your dongle. For around 16 bucks and shipped from within the USA its something to consider...

http://amzn.com/B00RF17866

The antenna plugs into the rtlsdr dongle, I've got this one.

I've used griffin tech power mate controllers with my sdr setup

Simple remap of the keyboard, spin nob for vfo, push down and turn for volume and click for mute in my case

https://www.amazon.com/gp/aw/d/B003VWU2WA/ref=mp_s_a_1_1?qid=1458704856&sr=8-1&pi=SY200_QL40&keywords=griffin+powermate&dpPl=1&dpID=41ip5QhZChL&ref=plSrch

That particular link is not available on Amazon but here's another one.
http://www.amazon.com/gp/aw/d/B00RF17866/ref=mp_s_a_1_3?qid=1425221337&sr=8-3&keywords=RTL-SDR+Blog&dpPl=1&dpID=51aeC%2BotSdL&ref=plSrch&pi=AC_SY200_QL40

I bought one of these and cut it down for 144.39Mhz (22.5in IIRC) for APRS:

https://www.amazon.com/Parts-Express-FM-Dipole-Antenna/dp/B000M9EREE

If you want another range you can cut accordingly.

Don't forget the F type balun:

https://www.amazon.com/gp/aw/d/B0002ZPIOQ/ref=pd_aw_fbt_23_img_2?ie=UTF8&psc=1&refRID=WVAR63WQK6KZVGP0GTRK

and an adapter to fit on your rtlsdr:

https://www.amazon.com/gp/aw/d/B00CP17WMG/ref=mp_s_a_1_1?ie=UTF8&qid=1469591788&sr=8-1&pi=SY200_QL40&keywords=mcx+male+to+sma+female&dpPl=1&dpID=31Q6jniv9vL&ref=plSrch

Sure!

Antenna: https://www.ebay.com/itm/Altelix-2-4-GHz-WiFi-24dB-Grid-Antenna-Long-Range-High-Gain-Outdoor-Directional/152930295331

Note: For this antenna, you will need to add about 3.5 cm of spacing on the reflector (Like https://i.imgur.com/ruqJmZ1.jpg) I made a 3D printable model just for this antenna that’s just the right size that you can download here: https://www.thingiverse.com/thing:3540047

LNA (Powered by SDR Bias Tee): https://www.amazon.com/Nooelec-SAWbird-GOES-Barebones-Applications/dp/B07GBFNV1H

SDR: https://www.amazon.com/RTL-SDR-Blog-RTL2832U-Software-Defined/dp/B0129EBDS2 (Note: If this thing gets too hot it will lose signal!)

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This is plugged into a Raspberry Pi 3+ running goestools (https://github.com/pietern/goestools)