Archive for November, 2012

The Android HT – Part 3

I received a comment on my previous post on The Android HT, pointing to this Android mobile phone plus UHF transceiver: Runbo X5. This is not quite what I described as the Android HT but this device is certainly interesting just the same.

Runbo X5 Android Phone with UHF Radio

Looking around on the web, I found this set of specifications. The frequency range for the “walkie-talky” function is listed as 400 to 470 MHz. The power output is not specified, but the UHF range is listed as 5 km. Some of the photos show a rubber duck antenna while others do not, so I suspect that the UHF antenna is removable.

Of course, the Android HT that I described was amateur radio only, no mobile phone capability included.

73, Bob K0NR

8 Dec 2012 Update: I just noticed that PD0AC highlighted a similar product on his blog, the OutFone BD-351-A83.

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New GNT Frequency

You may recall the story about the origination of the Golf November Tango frequency of 146.55 MHz. Unfortunately, we have discovered an oversight in the selection of this important frequency.

On the 2 Meter band in the US and Canada, we have two different channel spacings in use. Some regions use a 15-KHz channel spacing while other regions use 20-kHz channels. All regions do use 146.52 MHz as the FM calling frequency, but the other channels are spaced based on local practice. The 20-kHz spaced band plan has simplex frequencies that include 146.52, 146.54, 146.56 and 146.58 MHz. With a 15 kHz spacing, the resulting simplex frequencies include 146.52, 146.535, 146.550, 146.565 and 146.580 MHz. Clearly, the existing frequency of 146.55 MHz was only compatible with the 15-kHz band plan.

An investigation is underway to determine who actually chose this frequency, so the responsible party can be held responsible. Unfortunately, no one seems to remember how the frequency was actually chosen, so the investigation continues. In the mean time, The Committee to Preserve Golf November Tango met and decided to launch a fast-track project to establish a new GNT frequency. If at all possible, this frequency must be compatible with both types of band plans, so that a North American GNT frequency can be restored to its former glory, while fully conforming to local VHF band plans.

After an intensive 18 month investigation, the team was unable to find such a frequency. Even though they met weekly, usually while partaking of copious quantities of Gin and Tonic, they were unable to find a solution. It looked like the entire enterprise might be in jeopardy. But late one night, one of the committee members blurted out “hey, why don’t we just use 146.52 MHz since I already have it programmed into my radio?” By some quirk of fate, the other committee members thought he said “146.58 MHz”, which, in fact, does fit both band plans. The GNT frequency was quickly designated as 146.58 MHz and the meeting was adjourned.

So remember, when you are on the beach and in the need of liquid refreshment, make a distress call on the GNT frequency of 146.58 MHz.

73, Bob K0NR

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Easy Online Circuit Analysis

I was writing an electronics article today and started to do some circuit analysis by hand. It was a pretty simple circuit so I knew I could crank out the circuit analysis on paper but I started to think maybe there was a better way. I poked around the web and came across CircuitLab.com, a free, online circuit simulator.

A sample circuit from the CircuitLab web site.

As I gave it a try, I was amazed at how easy it was to use. I just started doing some simple drag-and-drop from my browser and the circuit quickly took shape. A few minutes later, I had my first analysis running and I started playing “what if” games with the circuit parameters.

OK, I’ll admit that the circuit I created was pretty simple but still, I am impressed. Oh, and did I mention that its free? If you have need for circuit diagrams and simulation, check out CircuitLab.com.

- 73, Bob K0NR

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Shack Talk on HamRadioSchool.com

I’ve been writing a few articles for the HamRadioSchool.com web site during the past few months. Most of these are aimed at newly licensed Technicians but other radio amateurs may find them useful.

Click on this link to go directly to the Shack Talk articles:

  • A Half-Wave Antenna for Your 2 Meter Handheld Radio
  • VHF FM Station At Home
  • Yes, Band Plans Do Matter

I also put together a quick reference chart for Technician License Bands and Modes.

Check out the other content available on HamRadioSchool.com.

73, Bob K0NR

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The Android HT – Part 2

My article on the Android HT generated some interesting comments and ideas. Thanks so much! One of the main themes in the feedback is to have the radio be “faceless”, with the user interface done on a mobile device (i.e., smartphone or tablet). The mobile device would communicate to the transceiver via Bluetooth (or maybe WiFi). This approach has the advantage of separating the radio hardware (which probably doesn’t need to change very often) from the compute/display hardware (which is on a faster-paced technology path). I went ahead and hacked together a concept photo of such a device (click the photo to enlarge it). This device could interface with any mobile device that has a Bluetooth interface, so it would be independent of OS on the mobile device (yes, you could use your iPhone).

Such an approach opens up a variety of use models. Imagine sticking the transceiver in your backpack and using an app on your smartphone to enjoy QSOs when hiking. Alternatively, the radio could hang on your belt. At home, the radio could be left in some convenient location, connected to an external antenna on the roof and operated from the mobile device. (Low power Bluetooth is said to have a range of about 10 Meters.)  These are just a few thoughts…I am sure you can think of others.

I would expect the original Android HT concept to be easier to use for casual operation, due to the All-In-One Design with dedicated hardware volume control, channel select and PTT switch. I am assuming those functions would be implemented in software in the faceless implementation, which would likely be less convenient. Most mobile devices have their own GPS system included, so that would mean one less thing that has to be in the radio.

The other idea that surfaced in the feedback is using Software Defined Radio (SDR) technology to implement the transceiver. This would provide a higher degree of flexibility in generating and decoding signals, enabling additional areas of innovation. That is a great idea and will require a whole ‘nuther line of thinking.

73, Bob K0NR

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