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4 votes
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Transmitting Video Underwater

Here is some useful scholarly information about the signal attenuation (in dB) of EM waves through freshwater at various frequencies and depths. You will find a formula that you can use. You will also ...
Mike Waters's user avatar
  • 8,071
4 votes

What is the legality of data modes over UHF/VHF in the US?

You may be able to operate the device without consideration of your amateur radio status. CFR 47 Part 15.231 permits the low power use of 433 MHz without a license provided certain transmission ...
Glenn W9IQ's user avatar
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3 votes
Accepted

What is the legality of data modes over UHF/VHF in the US?

Telemetry is explicitly allowed in §97.111. You must use an authorized "digital code", which probably means ASCII. And you must use a publicly documented technique. I don't see any ...
Phil Frost - W8II's user avatar
3 votes

Transmitting Video Underwater

SSTV could be an interesting answer here. Bandwidth requirement is about 30 KHz to reach your goal of 1 frame per second AND it's proven tech on HF bands... though you'll need to multiplex the video ...
webmarc's user avatar
  • 4,289
2 votes

Is it legal to make transmissions to one's own auto-confirming radio with the intent that a non-licensed person read the messages?

Perhaps a good lawyer could help you argue for some sort of loophole here, but this this certainly seems to fall within the intent of the § 97.113 Prohibited transmissions section of Part 97. Both: (...
natevw - AF7TB's user avatar
2 votes

Transmitting Video Underwater

Any antenna under water is creates a far more difficult problem than that of the main focus of the school project. I would put a WiFi transmitter (ESP32, et.al., inexpensive loss if drowned) on a ...
hotpaw2's user avatar
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2 votes

How to make GRC flowgraph run and stop automatically during some period

This is the sort of task for which it is at least easiest to do outside of the model of GNU Radio Companion. That is, you would take the generated code and instead of executing it directly, modify it —...
Kevin Reid AG6YO's user avatar
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1 vote

Aside from repeaters, what station types allow automated transmissions?

Certainly unattended packet radio stations can operate without a control operator present. Not just digipeaters, but store-and-forward messaging systems and also the Packet BBS systems. Of course, ...
SDsolar's user avatar
  • 2,087
1 vote

Wireless temperature data logger in the USA on 433MHz

In the US, if you don't want to reinvent the wheel then your easiest solution would probably be APRS, more specifically the Citizen Weather Observer Program, which is a standardized system to send ...
rclocher3's user avatar
  • 9,242
1 vote

Wireless temperature data logger in the USA on 433MHz

Legal discussion To ISM or not to ISM, that is the question So, in Europe, 433 MHz is an ISM band – you could even operate a device there if you weren't a licensed Ham! That also includes the fact ...
Marcus Müller's user avatar

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