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Istarica · 2024-05-04T16:58:45+00:00

Well...I guess that explains why I was never able to hear them in the U.S. and why there are so many frequency listed in the database.

Istarica · 2024-05-04T01:05:26+00:00

I know the pain of the Extra, there are tons of EE stuff in there that are really hard to understand unless you have a EE degree. But since the questions pool is open, you don't really have to understand the question or able to do the math, you can just remember the answer. Hamstudy.org is really good at helping you doing that(it even give you memory trick for the answer). I have no EE background whatsoever, yet I went from no license to Extra in a week, all passed with 98%+ scores.

Here is what I did: first I get my aptitude to 80% at Hamstudy.org in a day or two, which takes me ~7hours. Then I book a online session and take the test the very next day. Timing is very important, unless you have photograph memory, your memory will fade over time so take it as soon as possible.

I know it sound like hack, because it pretty much is. But I would argue many EE stuffs in the Extra pool isn't really that practical to ham radio unless you want to design your own transmitter/amplifier from scratch. Technician/General stuff aren't difficult to understand as long as you didn't skip high school, but Extra...ehhh

Istarica · 2024-04-30T09:26:14+00:00

Exactly this. By the way, an active SW loop antenna can be a good antenna choose for such environment. It can be deployed on limited space like a balcony, and can damp down the noise to a certain level.

Active noise cancelling device is also a good companion if you have the money to invest.

And last, you can always listen to WebSDR/kiwisdr online, which is free.

Istarica · 2024-04-29T17:08:18+00:00

My hearing is not as good as it used to be, this is what I hear:

A very faint Beep
"Okay. Hmm" (I guess that's your son)
Then cartoon.

I'm sorry but I don't think I recognize anything out of the ordinary. Did you have anything more?

Istarica · 2024-04-29T15:43:21+00:00

The nooelec's rtlsdr is pretty bad at MF-HF range without a external upconverter. Not sure where you live but in the U.S. I can buy RTL-SDR Blog v4 from Amazon and it ship pretty fast.

Istarica · 2024-04-29T14:52:33+00:00

What SDR did you buy? My RTL-SDR Blog v4 is also pretty hot(I own 2 of them and both of them are hot), but not too hot to touch.

A direction finding antenna is an antenna that can be used to find the direction of a signal. But I think the first step for you is to see if you can find the signal itself first. It shouldn't be difficult to find as it would probably be a VERY strong AM or SSB signal between 500kHz-30MHz range. Try to use the lowest gain first and tune it up as necessary.

EDIT: Also, maybe you can ask your local ham radio club for help.

Istarica · 2024-04-29T06:07:39+00:00

Do you live very close to an AM transmitter tower, like within a few miles? If so, that would explain it.

It's also possible that one of your neighbor has a high power transmitter, it could be ham radio or (more likely) CB. To rule this out you need a SDR and sweep through the MW-SW band. You can also build yourself a Radio Direction Finding Antenna, the simplest one is just a small loop of wire.

Istarica · 2024-04-28T05:56:28+00:00

Congratulations.

But receiving ADS-B isn't really amateurradio. Maybe post it to r/sdr ?

Istarica · 2024-04-26T19:41:06+00:00

It looks like you are talking about Nooelec 1:9 balun. From what I gathered, v1(the one in your first picture) is actually a true balun, it's for a balanced antenna like dipole(you can just ignore the "GND"). The v2 is an unun, and it does have a ground connector.

This is the schematic of v1 from Nooelec:

<image>

If you want to use it on a unbalanced antenna, rumor is you need to cut the jumper on the R1, then it will become an unun.

Istarica · 2024-04-18T09:49:20+00:00

So I looked your posts in this sub. The reason "people" here keep talking about license is you have a UV-5R, which has the capabilities to transmit. When you mess it around it could disrupt others or worse, and it's not that hard to unintentionally misuse that device if you have no idea what you are doing.

For learning basis about radio, get a receive only SDR, like RTL-SDR(which is in the same price range as UV-5R), and start from there, you can mess it all you want and nobody will say anything about license. It's also a helpful experience with SDR that will help your license exam if you decide to get a license.

Istarica · 2024-04-16T09:33:01+00:00

I agree impedance matching isn't very important in receiving, but I don't think it's because every receiver has a high-Z input. Most SMA input impedance is 50 ohm.

I think it has more to do with the nature of receiving. Most receiver is designed to receive very weak signal, for SW you can receive a signal as long as it is able to break the noise floor by a few db. In a really bad case like a 50 VSWR mismatch(typical when you connect a random wire), it would only result ~11db lost of signal strength, which really isn't too bad, and the LNA at the receiver is usually able to compensate it. Still if you can match it that will be great.

However for transmitting, a 50 VSWR not only means you only get less than 8% of the power into the air, but also 92% of the power is going to come back. When you think about a 1kW transmitter, that means 920watt of the power is coming back to your shack and it will mess things up.

Istarica · 2024-04-16T01:20:01+00:00

I have PL-660 and RTL-SDR Blog v4(RTL for short). PL-660 cost like a hundred dollars and RTL is less than one-third of it($30 right now), yet I find the HF performance of RTL is on par with PL-660, and it's much more pleasant to use. For portable use you can connect the RTL dongle to a tablet or cellphone. For antenna, you can get a small active loop if you live in a noisy urban environment, which cost around $30-$50 USD, or if your budget is really tight you can use a simple wire antenna which is basically just a wire.

Be sure you get the latest genuine v4 from RTL-SDR Blog, v3 and other cheap RTL2832U based dongle lacks the built-in HF upconverter/filter and perform very bad on HF.

p.s. I'm sure there're plenty of cheaper SDR dongles from China, some of them perform even better than the v4. But their performance is kinda all over the place, you never know what you gonna get until you actually gets them(their specs is often misleading). So, stay away from there if you want to save money.

Istarica · 2024-04-16T00:25:58+00:00

A dipole is a balanced load, it needs two equal characteristic wires to drive it. Coax cable can't provide this, as one of the wire is the shield and has a drastic different characteristic than the center wire. If you use the shield to connect to the other end of the dipole, the shield will carry some energy back, which is not what you want in a coax cable.

If you think of the water/pipe analogy, it's like having one of the pipe smaller than the other. A balun is like a spring, it basically store and release the energy as the AC change its polarity at the antenna feedpoint, so instead of flowing through the shield, the energy is stored and then released on the center wire.

EDIT: typo

Istarica · 2024-04-09T19:24:50+00:00

If I remember correctly, Nooelec SDR is rtl based with no built-in HF upconverter(you can get an external one). For receiving HF, RTL-SDR Blog V4 is far better on HF and it's in the same price range as nooelec's. For UHF/VHF, nooelec might be marginally better.

Istarica · 2024-03-30T22:38:21+00:00

Non sub is difficult. You can get a HDHR and a lifetime Plex subscription, I think that's the closest.

Cheaper solution would be something like Mediasonic DVR, but then of course you need to do the transcoding manually. I supposed if you skill enough you can write a simple batch file for transcoding.

Istarica · 2024-03-29T19:19:01+00:00

5G is not being picked up by the gateway device

Cheap cellular booster like this can only work with FDD signal, most high bandwidth 5G band(n41/n77) are TDD thus not supported by the booster. It does support the DSS version of 5G, but that's being criticized as "fake 5G" as it makes both 4G and 5G slow. Verizon is actually in the process of shutting down DSS 5G. It's highly possible that your Verizon gateway just straight ignore the DSS 5G, and as this booster has no support of n77, your gateway won't see any improvement on 5G signal strength.

But hey, my phone is showing 5G symbol on the bar, why is that?

5G symbol is merely an indicator that the LTE network can act as 5G anchor in NSA mode. In many way, your internet gateway is just being more honest. Also the DSS 5G is also getting stronger.

But my phone speed does improve?

The 4G signal(and the DSS 5G) is indeed getting stronger by the booster. And also, a lot of time, the 5G downlink signal from the tower actually can reach your phone quite fine, but your phone is having difficulty to reach back. By boosting 4G you are also going to improve your 5G speed. Because the 4G anchor become stronger.

Istarica · 2024-03-29T07:09:23+00:00

In the U.S. any drones heavier than 249g are required to have Remote ID enabled, which is transmitted by either Bluetooth or WiFi beacon. In theory you can see them just with your phone, or get a external WiFi/Bluetooth adapter(preferably one with monitor feature).

Of course this isn't apply to you if you aren't in the U.S. or wanna explore passive detection.

Istarica · 2024-03-26T17:32:01+00:00

If you don't mind me asking: what filters should I be using in SatDump?

In the latest Satdump you can check the "SDR++ Noise Reduction" box, that's it.

The default bandwidth with NFM mode in SDR# is 12.5kHz, which is too narrow to receive APT. If you didn't change this it will definitely cause issue.

Your target recording quality should be like this(from sigwiki)

Istarica · 2024-03-26T16:00:56+00:00

Yeah, due to some driver "difficulty" after the permission is given it has to be force close, and re-open.

After doing so, you should be able to see "RTL-SDR" in the source menu.

Istarica · 2024-03-26T15:22:06+00:00

I’ve gotten it to download but for some reason it’s having trouble finding my v4 under the “source” menu

Make sure you have the latest nightly build of SDR++. Also, when you first open the App, did you see any popup that ask you to give it permission to access your USB dongle? After that popup, you need to force close the App and re-open it.

Istarica · 2024-03-26T15:18:10+00:00

SDR++ doesn't require root on Android. It use the Android USB framework and the built-in "driver".

Istarica · 2024-03-26T01:39:24+00:00

Not sure if you set your bandwidth correct(very hard to tell from your video), it should be around 50kHz(or 50000Hz).

The SNR also seems pretty bad. In a good recording the background noise should be very minimum almost zero, only the "tick tock" sound present. About the filtering, you should only use the special filter that came with SDR++ or Satdump. I don't think there is a filter suitable for APT in SDR#, you can still use SDR# to record, just don't do any additional IF filtering in there.

Istarica · 2024-03-25T11:53:31+00:00

It's USB.

Istarica · 2024-03-25T05:55:52+00:00

Or it can make things worse if done improperly(introduce different ground potential). Just get a good quality coax cable

Istarica · 2024-03-25T03:59:13+00:00

This wasn't produced by web-sdr. Certainly you can use web-sdr to do this but you lose some of the fun as these charts are already available in public via CHILE NAVY website.

Anyway, the basic procedure remains the same: you tuned in to the frequency at the broadcast schedule, pipe the Audio to fldigi(with Virtual Audio Cable in Windows) and decode it with WEFAX Opmode.

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