Архив за 06.10.2018

Comment on Connecting an RTL-SDR Panadapter to a uBITX Transceiver by Drone

Try hanging around here: softrock40@groups.io, but understand that these SDR’s they’re using are direct down-converting/sampling types. Pre-built radios and kits can be bought here: http://fivedash.com/. The $21 “Lite” receivers are popular as pan-adapters, but you will need to supply the correct crystal or synthesized L.O. for your particular radio’s IF scheme, and different radios have different connection techniques. Ask in the Group about your particular radio. I’d be surprised if the uBITX hasn’t been done already.

Comment on Connecting an RTL-SDR Panadapter to a uBITX Transceiver by Drone

The article source location has unreasonable restrictions on commenting, so I’ll drop this here:

“Pan-Adapters” are sometimes referred to as “PAIN-Adapters”, especially if you use a SDR. There are good reasons for this…

1. Many SDR’s radiate out the antenna port (especially direct conversion SDR’s). An SDR without a front-end amplifier, and/or directional isolator may struggle with unwanted signal leakage out the antenna port. This can cause real problems when you connect the SDR to your radio’s IF, especially if your radio is a transceiver with a shared transmit/receive IF.

You have to be careful with this. If you don’t you may (at-least) transmit unwanted signals. Isolating the SDR from the IF is best done using a high isolation physical relay or seitch that not only isolates the SDR input during transmit, it terminates it. Also to avoid unwanted double termination, the relay or switch should be a break-before-make type.

Even with a physical switch or relay you may find your isolation isn’t good enough and you will need to add more shielding, capacitor bypassing, and/or series chokes at critical points. Remember, a non-isolated SDR connection may not only be a source of unwanted radiation, it may also act as a feedback path that causes instability.

2. Tapping the lower IF frequency will result in less unwanted signal products during receive, but more during transmit. The opposite is true for tapping the high IF.

3. Simply connecting the SDR to the IF chain will cause an unwanted impedance mismatch. Buffer or pad the connection to reduce this effect.

4. Depending on your system design and type of SDR (down conversion or direct conversion), sometimes a diplexer can be used to good effect to isolate unwanted signals and impedance mismatches introduced by the SDR.

Troubleshooting Help • Re: Meu dongle para de funcionar

Caro amigo,
Informe o sistema operacional e a versão do SDR# que vc esta usando. Eu tenho um notebook DELL ambiente Win10 e versão 1.0.0.1332 do SDR# e não tenho este problema que vc apontou. O outro amigo respondeu com a sugestão de ser usado um outro aplicativo como HDSDR, que funciona bem também.
Aguardo informação.73.

Statistics: Posted by py2wpf — Sat Oct 06, 2018 10:58 pm


Troubleshooting Help • Re: Overheating issue with usb 3.1

The V3 is definitely going to feel hotter than the plastic devices because the case is acting as a heat sink. The plastic case devices have issues at Lband frequencies because the PCB gets too hot inside, causing the PLL to lose lock.

Normal current draw is just under 300mA. Some faulty USB current meters will read around 200mA though.

There is a rare problem however that affects all brands of RTL-SDR dongles and that's faulty RTL2832U chips. They work correctly at first but begin to fail over time, and start to draw higher than normal current. From our stats we see that happening at about 0.3%. If you suspect that your dongle has that problem there please feel to contact us.

Statistics: Posted by rtlsdrblog — Sat Oct 06, 2018 10:45 pm


Comment on YouTube Talk: Evaluating 9 of the Best Single Board Computers for Ham Radio SDR Systems by Val

Yes, that’s a good point

Comment on YouTube Talk: Evaluating 9 of the Best Single Board Computers for Ham Radio SDR Systems by Timmy

Internally there are two USB 3.0 ports on the processor used.

On the XU4 one port is already used for the gigabit NIC and the second one is free (in fact it has a two port USB 3.0 HUB chip on it)
https://www.hardkernel.com/main/products/prdt_info.php?g_code=G143452239825&tab_idx=2

On the HC1 one is already used for the gigabit and the second one has a JMS578 USB 3.1 Gen1 to SATA 6Gb/s Bridge Controller soldered onto the board so that board is only useful if you are using a USB 2.0 device.
https://www.hardkernel.com/main/products/prdt_info.php?g_code=G150229074080&tab_idx=2

Comment on YouTube Talk: Evaluating 9 of the Best Single Board Computers for Ham Radio SDR Systems by Val

There is one more interesting option: Odroid HC1
It’s almost the same thing as XU4, so it’s a powerful beast, but it has no HDMI socket, and it’s built on a huge heat sink that works as a housing for the board and HDD or SDD that you can connect right to the board.
It means that you can connect HDD or SDD and log a ton of data coming from RF.
It has a very fast Gigabit Ethernet so it would also not be a problem to download the data from it.
Armbian works great on it.

There is however an important parameter in single board computers: required power supply. If you want the computer to be portable I highly recommend getting one with Mini/Micro USB socket for power, then you can power it from a good power bank no problem. I don’t think it’s possible with Odroids.

Знакомые просят помощи, нашли антенну, не могут понять на какой диапазон. Есть знающие люди?…

Знакомые просят помощи, нашли антенну, не могут понять на какой диапазон. Есть знающие люди?

Наконец-то собрал приемник до такого состояния, чтобы можно было антенну…

Наконец-то собрал приемник до такого состояния, чтобы можно было антенну подключить. В основе — Лаповок. Пока без фото, к сожалению. База — дискретные полевики.

Signal Identification Help • Figuring out partly known signal

I wonder if there is good tools for figuring out signals that are partly known.
I have an USB 433MHz dongle, and I've been trying to communicate with it using small SPI-connected radio boards.

I know the central frequency is 433.90 MHz and that it uses GFSK. Data rate is 9600 bps (default), but I have no idea of the deviation or number of preamble bits etc.

I managed to receive data from the dongle, but I haven't been able to send to it, and I have no idea what's unacceptable about the frame I'm trying to send to it. I haven't even got an RSSI-reaction.

Statistics: Posted by turboscrew — Sat Oct 06, 2018 4:26 pm


Перевод
Рубрики
Октябрь 2018
Пн Вт Ср Чт Пт Сб Вс
« Сен    
1234567
891011121314
15161718192021
22232425262728
293031