Showing posts with label Radio. Show all posts
Showing posts with label Radio. Show all posts

Tuesday, July 28, 2020

Cognitive Radio

Via Neural Network-Enhanced 'Cognitive Radio' Communicates With ISS

To understand Cognitive Radios, you have to understand that the term Cognitive Radio came directly from Joseph Mitola's research in the mid to late 90's.

He was well known for being a software guy who got into RF. His early research was in software radios and the term "Cognitive Radio" was coined in 1999.

To understand why "cognitive radio" became a thing, one has to understand why "software radios" became a thing.

First, virtually all radio systems (even those developed now) are done by deciding the spectrum, modulation, and propagation methods up front. You do this so you can decide what the link budget (bandwidth) of your connection is, determine whether the signal is analog or digital, pulsed or CW, the modulation, demodulation, filters, mixers, noise floor, sampling, amplification, antennas, etc. This is why you typically see new wifi and cellular systems determined "by spec". The spec informs the hardware design and vice versa. This is also why you often hear about bandwidth allocation as a hot topic - not only is bandwidth fundamentally "squatters rights", so that organization and adherence to rules is important, the bandwidth allocation also fundamentally informs which physics are important and therefore the hardware of the radio system itself.

Second, the digital theory of information fundamentally transformed radio, and was in the process of transforming radio for several decades. There was a lot known about the digital equivalence of physical devices like filters, and phenomenon like noise, and ideas like channel capacity, but due to the nyquist theorem, it was actually very difficult to take advantage of any of the knowledge gained because computers were simply not fast enough to perform the necessary mathematical operations quickly to convert voltages to bits, compute, modify the bits, then convert back to voltage - especially at higher and higher frequencies. (Notice how your communications devices get faster and faster data rates over time? You can thank the fact that computing hardware is getting faster and faster.)

With the advent of fast computational devices (DSPs, mostly) it became possible to implement a lot of the theoretical advantages of digitized waveforms.

Third, RF designers started to look at the fundamental hardware building blocks of a radio, especially the filtering, modulation/demodulation. and mixing stages - which were often analog components that were "off the shelf" and fixed quantities, and created theories around how to create generalized digital representations of these devices. Once the fundamental building blocks became well understood in terms of how to build software representations of these devices, and hardware became fast enough to implement some of these software representations of once fixed hardware devices (in practice, this is still extremely primitive - even in 2020 terms), researchers began to earnestly look at how one might be able to create dynamically reconfigurable RF systems.

And the representation of these dynamically reconfigurable RF systems? Of course, it is done as a language, and therefore, programmed in software. Hence the field of "Software Radio."

Now that you realize how radio got into the software domain, you have to understand that the term "cognitive radio" is just any software radio that implements Mitola's Congitive Cycle, which is basically just a feedback loop, where a radio listens to its environment and then adapts its RF operation to best reach the receiver.

There was a program in 2012 called COMMEX (Communication through Extreme Interference) by DARPA that was ultimately won using a Cognitive Radio approach.

This is just a vastly simplified explanation. To really understand the concept of how AI can be used to steer the software radio system to receive receivers through difficult links / signal paths, you have to understand that AI is just a combination of linear algebra and statistical mathematics being used to solve objective functions. But now, maybe you have more to explore in terms of why AI and Cognitive Radio became a thing, and why it might be useful for this kind of situation.

Friday, September 6, 2019

UHF iPhone Case Giveaway

Sign up for the Radioddity newsletter for a chance to win the iPhone case that is also a battery and a UHF radio.

About Radioddity GM -Series
As a UHF radio, it provides a LCD screen and 4 function keys for simple operation, that’s why it fits for the security team, construction team, warehouse, factory, kitchen staff, hotel, retail store, school staff, wild trip, etc. Battery phone case design makes it portable in your daily life, you can add as many sets as you want and they work great together.
➥ Frequency range: 400 - 470MHz
➥ Number of channels: 16
➥ Output power: 1.9 +/ - 0.2W
➥ Communication distance: 2 - 5km (1.24 - 3.1 miles)
➥ Rated voltage: DC 3.7V
➥ Input voltage: 5V 1A
➥ Channel spacing: 25KHz
➥ Battery: 3500mAh ( included in product )
➥ Battery standby time: 120 hours
➥ LCD crystal display screen
➥ Ultra long-distance and long working time
➥ As a phone case for IP6, IP7, IP8, and IPX

Large Capacity Battery
The GM series walkie-talkie has a large capacity of 3500mAh Li-ion battery for long time working, it is much higher than any other two-way radio. What’s more, it can charge your cell phone as a power bank.
What's in the box:
1 * Radioddity GM4/5/6 Two-Way Radio
1 * Radio Power Cable
1 * Power Bank Cable
1 * Short Antenna (3km | 1.86mi)
1 * Long Antenna (5km | 3.1mi )
1 * Antenna Cap
1 * Lanyard
1 * Instruction Manual
1 * Packing Box

Saturday, January 13, 2018

BaoFeng BF-T3

I saw this post about the BF-T3 on the BaoFeng UV-5R Yahoo Group. I recently looked the BF-T3 up on Amazon and it looks like it is being sold under a bunch of different names. That's not uncommon for these Chinese radios to be rebranded.
"BaoFeng has a new HT. 
Over the past several months I had been exchanging occasional emails with a “Robert Frost” who had been asking me questions about the features needed or desired in a new Amateur Radio. Recently he informed me that BaoFeng has a new radio about to be released and he asked me to review it. I agreed, and they sent me a pair of their newest radio. This is NOT an amateur radio, and it does not even resemble anything we had talked about in the previous emails. This is a traditional FRS radio – complete with blister pack packaging. (See pictures 1-3) 

The radio is the BF-T3 “Walkie Talkie Set” sold in two-pack. The package contains two HTs and a User’s Manual printed on both sides of a single large sheet of paper. (Pictures 8-11)
Interestingly enough, there is a barcode sticker on the package that I received but not a UPC code (perhaps an Amazon item number code, these radios are now available on Amazon at $17-18 a pair). The barcode sticker shows the product as “Kids Walkie Talkies BaoFen.” (Picture 2)
The package includes the FCC logo that is supposed to mean Part 15 compliance, but nothing on or with these radios indicates that they are actually approved for FRS use (although they do appear to meet all the requirements for the new 22 channel FRS radios that go into effect with the revision of Part 95.)  
The radios themselves are black with silver trim and look pretty much the same as most other FRS radios other than that these have no knobs and 9 buttons to control the radio. The size is appropriate for average tween to adult hands but might be a bit large for smaller children. The PTT button is labeled TALK and is located at the center front of the radio not on the side. The speaker grill appears larger than it actually is. (Picture 3)

The User Manual (pictures 8-11) contains a few minor errors but is far better than the manuals provided with the vast majority of Chinese radios. The manual is what I would call an Almost-Final-Draft and seems to have been written as the radio was being designed rather than after the radio itself was fully completed. For example, at one point the User Manual says “There are two kinds of sub-channels:” and then goes on to describe CTCSS, but it never does mention the other kind (presumably DCS, which this radio doesn’t have). 
Each radio uses three AAA size batteries. The area where the batteries go is sized to hold four AAA batteries but there are only contacts for three. (Pictures 6-7)

In true BaoFeng style, these FRS radios also include the LED light on the top (on/off only, no flashing setting). (Picture 4). The Push-to-talk (PPT) button is the large button on the front center of the radio, and is labeled TALK. Other buttons are labeled LAMP (turns the flashlight on and off); a Z shaped arrow (activates scanning); a musical note (sends the call tone); Up and Down pointing triangles (increase and decrease the volume, also change the settings in each of the menus); MON (the monitor button); MENU with a picture of a padlock (press the button one to four times to bring up different menus, press and hold to lock the keypad); and the power button with the common power on/off icon. (Pictures 3 & 11)
Hand a pair of these radios to a couple of six year olds and they will quickly figure out how to use them, although they probably won't be able to change the channel, the CTCSS tones, or the call tones. 
Speaking of the call tones, the package (picture 2) says five of the call tones are animal sounds -- fortunately this is not true. All the call tones are typical computer style ring tones and musical riffs.
Other than the unusual position of the TALK button, these radios work pretty much just as you would expect of any 500mW FRS radio. Audio is reasonably clear. Range is nowhere close to the claimed "3KM Call Range Distance" but in my suburban location they worked reliably for about 1/2 mile (about 0.8 KM) which would be typical for this sort of radio. I'm sure the call tones would be audible at longer distances than ordinary voice. These radios might manage 3KM from one mountain top to another or between a pair of boats on a large lake, but not on the ground in a normal urban or suburban area. The range claim on the package is no worse than those on any other FRS radio that I have seen. All FRS radios claim much more range than the radios actually accomplish. 
One feature that really does not work is the belt clip on the back of the radio (pictures 5 & 6). These are molded rigid plastic. You might be able to thread a belt through the clip, but unless the belt is VERY thin, you won't be able to slip the radio on and off the belt using it as a belt clip should function. Also, the catch that is supposed to hold the clip on the radio isn't very secure. The clip comes off the radio easier than it would go on or off a belt. 
One thing not visible in the photos is the earphone/mic jack on the top of the radio (picture 4) between the LED light and the fixed antenna. The User Manual says that this jack is for an earphone/microphone and that you need to use the one provided or it could damage the radio. There was no earphone included in the package (and no place for any earphone). Based on the warning I didn't try experimenting by plugging anything into the jack, but I would hope that it takes the same earphone/mic as most cell phones.

Overall, the BF-T3 radios are perhaps a little better than the typical 500mW FRS radio of a few years ago. They certainly work well enough for my grand-daughter and her husband to use back and forth around the stable and field while taking care of the horses. I don't know what price BaoFeng has in mind for these radios. Anywhere under $20 for the pair, I'd consider them a reasonable. If the price were above that, most people would be better served stepping up to a better radio."

Thursday, January 11, 2018

Wednesday, March 8, 2017

Wireless Hacking

"His plan involved setting up a transmitter not far from the lecture (supposedly in the theater that his father, a famous stage magician, owned) that would overwhelm the signals from Cornwall. His transmitter, he claimed, was not run at full power: while it was capable of outputting 8 or 9 Amps, he turned it down to 2.5 Amps. He didn’t simply block the signal, but instead transmitted his own morse signal for a short time, claiming that he “studiously refrained from all unnecessary interference”.  
His plan worked. Towards the end of the lecture, Maskelyne’s signals were picked up by the receiver, decoded and noted by Fleming, who wrote to the Times complaining of “Scientific Hooliganism”."

Friday, September 16, 2016

TalkiePi - Raspberry Pi Walkie Talkie

"talkiepi uses Mumble for its voice communication protocol. Mumble is an open source, lightweight, high quality voice chat system designed for use by PC gamers. Mumble lent itself perfectly for this use case. There are already software clients for all platforms (Mac, Win, Linux, IOS, Android), meaning you can talk with your talkiepi using your phone or computer, and you're not limited to just talkiepi devices! By utilizing Mumble channels, user registration, and access control lists, you can configure different groups of talkiepis, just like using different channels on a traditional walkie talkie.

talkiepi is built utilizing a Raspberry Pi, USB speakerphone, some basic electronic components, and a 3D printed enclosure. talkiepi runs amumble client that has been designed specifically for push to talk via the push button interface. After it is setup on your wifi network and the software is configured, talkiepi will require little to no maintenance to use."

Wednesday, August 31, 2016

All the Light We Cannot See

So not really about ham radio, but radios play a central role in All the Light We Cannot See by Anthony Doerr. The book is set in WWII and tracks a young French girl and German boy as their lives intersect thanks to the magic of radio. I just finished it and it is definitely one of my favorite reads in the past couple of year.

Monday, July 11, 2016

Saturday, January 9, 2016

Alinco DJ-X11

Mike's got a new favorite - Alinco DJ-X11:
"The Alinco DJ-X11 is a wide-band all mode portable that has IQ output so it can be used as a limited sound card based SDR and it also has the option to output base-band audio also known as a discriminator tap the can be used with any app that needs unfiltered audio (PDW, Unitrunker)."

Friday, December 11, 2015

Advanced Tin Foil Hat

Shield: The World`s First Signal Proof Headwear
Stylish & Comfortable Signal Proof Hats That Incredibly Fit And Reflect Electromagnetic Waves.

Tuesday, December 8, 2015


Along the lines of the goTenna... the Beartooth:
"Beartooth is a software defined radio peer to peer communication platform that encases your phone and doubles your battery life. Our proprietary software defined radio allows your smartphone to communicate even without cellular or wifi service. We allow for Push to Talk "PTT" voice communication, text messaging, and geolocation sharing on our offline maps."
"Our product will require FCC approval. We are currently working with attorneys and technical advisors who specialize in FCC approval. Our products are designed to meet the technical and legal requirements of the FCC, and we anticipate a favorable part outcome."
The audio on this video is spotty and you still only get high level info, but they do mentions amateur radio as a target market (along with consumers.)

Thursday, December 3, 2015


So, I'm gonna have chips for bluetooth, wi-fi, NFC, and Li-Fi in my devices?
"So, will Li-Fi be a competitor to Wi-Fi in the future? 
I highly doubt they will be competing technologies and will most likely be complementary if anything. For instance, you could have a situation where you have Li-Fi overlaid on top of a Wi-Fi network in high density environments such as a conference hall. The Li-Fi can support the dense number of users and wouldn’t interfere with the Wi-Fi network. In terms of home uses, it is unlikely to become commonplace as you would need to have an Ethernet connection to each light and the lights must remain on for communications. Most home users like the ability to use the internet in the dark and that is not possible with Li-Fi."
1 kbps (infrared light)
1 Gbps (visible light)
224 Gbps theoretical

1.3 Gbps (802.11ac, 3 spatial streams, 80 MHz channel, SGI)
10 Gbps theoretical
(802.11ax research in 5 GHz band)

Friday, September 25, 2015

Weather Alert Radio System

This seems like a crazy deal... an Eton ZoneGuard+ Weather Alert Radio System with Wireless Alert Modules for $10. It's weather alert radio plus modules you can place throughout your house, so you can be notified anywhere.

Tuesday, August 4, 2015

County Comm GP-5/SSB

John reviews the County Comm GP-5/SSB Handheld Receiver (AM, FM, SW, USB, LSB ~1.7 to 30 MHz):
"This is not your typical portable Shortwave radio, but a state of the art SDR with full frequency range and true USB/LSB filters.
Whether your requirements are for EmComm, survival kit, or you're a ham that can't leave his rig behind when on vacation, this impressive handheld receiver is definitely worth considering."
I like the County Comm stuff - I've never bought any of the electronics, but I have purchased several odds and ends.

Wednesday, April 15, 2015

NOAA Alerts - Part 2

Looks like several folks liked the idea of a $8 NOAA Alert Radio, but Nate points out a nifty alternative...

Radio Shack All Hazards Weather Alert Clock Radio With Skywarn
"For less than $30, you can get a radio that does: 
- NOAA (with Specific Area Message Encoding, the display will alert and show the text even if the radio is in standby). 
- Your regular analog Broadcast AM/FM (Stereo, it has 2 speakers) 
- "Skywarn band" (Which is essentially 2m and 440).- AUX input. 
- Alarm clock (2 separated alarms can be set).
It has a BNC female connector like most scanners have, so you can plug it into an external antenna as well.
I use it some times when I want to monitor a nearby repeater."

Friday, April 10, 2015

NOAA Alerts

Speaking of NOAA alerts, this RadioShack SAME Weather Radio for $7.99 was getting a lot of praise on the 470 repeater the other day.

Thursday, March 5, 2015

Homebrew Uniden Scanner Enhancement

"Richk107 and myself have come up with another great hardware design. It will fill the gap for a needed piece of hardware left out in all Uniden scanners.

We all know our past endeavor called "Uniden homebrew remote head" was a real success and without Rich it would not be possible.

This new device will be totally open source. The schematics, The code & all the needed hardware will all be posted here. This new hardware design will cost you no more then $20-$25 depending on how your source your parts which i will also list. 
Hopefully Uniden will wake up and start adding this to all of its future radios...Stay tuned"

Tuesday, January 6, 2015