Monday, October 11, 2021

Why United States amateur radio can not evolve?


The title of this post sounds a little like a "Jeopardy" answer in the category of "Famous son inventors".  Probably, the question was "Beyond silencers, this son of a different American pioneer was also known for the growth of which hobby, which involves shooting things other than bullets into the air?"

1ZT: Getting your attention!

Its always easy to poke fun at the love of all things high frequency and possibly even one of the important founders of the Amateur Radio Relay League (ARRL) who we have to credit, much like the National Rifle Association (NRA), for embedding certain hobbies and perceptions into the DNA of Americans.  

This is none other than the old man himself, Hiram Percy Maxim, who is not only one of the co-founders of the ARRL, but also one of the early inventors of the firearm silencer and son of the mastermind behind the Maxim machine gun.

Did you know there was a more legitimate co-founder of the ARRL named Clarence Tuska?  He was also the person behind the much loved QST magazine and likely would be more apt to read an article like this compared to Mr. Maxim.  

Both of these "OM" helped evolve the world of wireless communications for hobbyists like us, but we are now at a time where we need to prevent us from facing extinction.

As an engineer,  Mr. Tuska is who promoted the use of the higher 200m and above spectrum rather then the lower 600m band and was much more focused as an experimenter with radio technology.  I like Mr. Tuska and what he did for the hobby in the United States, thanks to his awareness to share information in written form. Lets now jump into something fresh and new! 


I write this after sharing notice of an important evolution within radio technology which has not yet really come into wide spread use across amateur radio yet.  

Today, we can not wait around for QST to learn about the latest innovations.  Its right here in the digital domain is where you will learn about something new. And, by the time most people get QST in the mail, its out of date and more time is spent trying to find who to give it to! 

The Future.....

What I am talking about is known as a software definable front end preselector.  Those I shared this latest Crowd Supply project with immediately needed to point out that something like this is useless, since it does not include capability for our much beloved "HF" spectrum allocations.  

At $419 USD, it is expected to cover spectrum much lower in order to appeal to the amateur radio hobbyist to make it a worth while purchase.

This preselector is a versatile, highly useful tool for providing programmable bandpass filtering for a software-defined radio, among other applications. 

In the receive path, that filtering can be used to mitigate the effect of strong blocking signals; in the transmit path, it can be used to help reduce out-of-band radiation. 

ATEK1001 aims to provide an affordable filter bank for radio enthusiasts and SDR users. More of the technical specifications concerning the 485MHz to 7.7 GHz can be read about here

Starting so high into UHF spectrum even limits its applications for most of the amateur radio community members interested in bands such as 70cm, 1.25m, 2m, 4m, 6m and of course the rest of the HF band.

What makes the ATEK101 interesting is how small it is. 

Who cares. More money for another HF CW/DIGI Kit!!

For those interested in Software Defined Radio (SDR), this is where the market software defined radio front end (SDRFE) is really targeted.  Not the HF only operator who only chases CW contacts in South Dakota.

The popular Lime SDR and Lime SDR Mini are joined by a branded product also available via Crowd Supply called the Lime RFE which does cover the important spectrum we care about and is only a mere $699 USD and covers up to 3.5 GHz plus all the important amateur radio bands in between. 

It is however a much larger product. There is even a $549 USD option for those who do not need the cellular filtering and this will appeal more to frugal amateur radio operators looking for something new. 

If you wanted to experiment with RF filtering, the Lime RFE or the ATAK1001 are what is available today.   


SIDE NOTE:   Interested SDR for HF?   Get online for the QDX available October 11th at 2:00 PM EST until units sell out. 


Do I need a SDR Front End?

Reason here is to illustrate there are some interesting things taking place within the world of software "re-defined" radio worth keeping an eye on, but another area is the niche that the phase coherent software defined radio is filling.

We are jumping to a totally different topics here because I can not find anything about a dedicated HF only or even HF and VHF RFE to write about, but now I know I have your attention.  

A phase coherent SDR is a combination of multiple software defined radios which can act together or separate from each other to do interesting things.

Combining multiple receivers can act as a way to filter or combine signals and the provided "Kerberos" product was the first low cost way to do this with its four receivers which are identical in performance to the popular RTL-SDR V3 most who are reading this probably own already.

Software for Software Defined Radio

A challenge when the Kerberos first came to market in early 2019 was little available software to use it with and it also needed a little more horse power from a computer to utilize its capabilities.

Things changed for Kerberos when the Raspberry Pi 4 became available and it was far easier to use the Kerberos for applications like radio direction finding or using its phase coherence capability. 

Software also improved since 2019, with applications like SDRangel being one of the first to offer easy to use multiple receivers at the same time in a visual application.   

Using something like a Kerberos and its 4 separate receivers capable to tune to any approximate 2.4 MHz chunk of spectrum at one time means you can monitor multiple bands at the same time or even the same frequency via different receivers and find ways to optimize reception by using different DSP filtering tools.  

By the time many people got excited about the capability of the Kerberos, it was already out of production or sold at lower cost, but there is a new model called the Kraken about to be unleashed which will include five independent receivers.  so,  its time to jump onboard now if you want to do amazing things with a phase coherent receiver. 

There is a more polished software program specific for the Kraken, which can also be used with the Kerberos if you have.  

Many more traditional SDR programs like those which Rick W1RHS let us know about recently also exist now which can be used with phase coherent hardware.

During the October 19th session of the popular Northstar Digital Net managed by Jim WA2UMP,  some discussion about both phase coherent receivers and possibly other SDR topics like RFE will be mentioned. 

Steve K2GOG of HVDN will be available to share more details and field questions on some other aspects about software defined radio that hopefully, will make the likes of Mr. Tuska and Mr. Maxim proud. 

Please be sure to join us Tuesday October 19th at 8:00 PM Eastern Time on Brandmeister Talk Group 31630 if you are interested in topics like this on the evolution of amateur radio by using the future to do so thanks to DMR.

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