Monday, July 26, 2021

BREAKING NEWS: FM coming to US Citizens Band?


In other parts of the world like the United Kingdom and much of Europe, it has been possible for legal use of FM mode using 27 MHz Citizens Band for many years.

The United States has not made any major changes to its unlicensed radio services since the introduction of the 5 channel VHF MURS plan starting in 2009 and fully adopted in 2014.

Opening up the use of FM on the "CB" spectrum in the United States which currently uses AM and SSB mode is going to introduce some interesting dynamics if this long overdue change to FCC Part 95 is adopted. 

There are actually a number of other things mentioned in the July 15th 2021 WT Docket No. 10-119 that may catch your eye beyond just the petition raised by Cobra and President, two very well known vendors of legal (and semi-legal) CB capable equipment made for the US market.

What the Memorandum Opinion and Order on Reconsideration Would Do: 

  • Grant Cobra’s Petition requesting that the Commission allow FM as an optional modulation scheme for all existing 40 CB Radio Service channels (with AM remaining mandatory). 
    • Dual modulation would improve the user experience since FM provides benefits for some types of communications.
  • Grant Motorola’s Petition requesting that the Commission allow automatic or periodic location and data transmissions in the GMRS and FRS. The Commission’s rules currently permit the transmission of location information and brief text messages initiated by a manual action and automatic responses of location information.
    •  This action would assist users in tracking friends and family in remote outdoor locations (e.g. hikers, skiers, hunters). 
    • This action would permit automatic location information transmissions, as conditioned, on all GMRS/FRS channels where the Commission has allowed manual data transmissions, subject to the same technical limitations as manual data transmissions. 
  • Grant Medtronic’s Petition requesting the correction of typographical errors and rule changes in the Part 95 Personal Radio Services Rules Report and Order that inadvertently altered the substance of the Medical Device Radiocommunications Service (MedRadio) rules.
More details can be referred to here via the official FCC document 374114A1

Drama Alert : Amateur Radio and Citizens Band

For anyone who has been around "radio hobbies" for a while, they know that there is a very cautious relationship between those that hold amateur radio licenses and those who enjoy citizens band operation, along with the space in between the amateur 10m band and the legal 11m CB spectrum.

There are many radios capable of FM operation already and available for sale to be used on 27 MHz and there are also a few radios that can be easily modified to support FM in addition to AM.  A few vendors like Midland and Cobra produce different models of radios for various geographic markets that often just need a small change on the inside of the radio and a different model number or label on the outside.

A great and low cost option to experiment with FM when it becomes legal to do so in the United States is via the Midland 75-822 or Cobra 45WX series of radios.  

Wednesday, July 7, 2021

HR3:2021 Visualized Results

With our first event complete, many of the station sponsors that participated have started to publish articles in club newsletters.

Certificates of Achievement are now being issued to those that submitted electronic logs and printed certificates are being mailed to those that donated to the event's fund raising goal honoring Bannerman Castle Trust.

Summary of  the event is below and at 

While we are showing an entire list of all contacts  on the Hudson River Radio Relay event page and which of the eight special event stations they were able to contact, it is time to release files to best visualize all the contacts made by station using Google Earth. 

Special Notes: 

  • HVDN used the K2DSL ADIF to KML conversion tool to take our logged data from the fantastic N3FJP AClog program to generate these Google Earth files.
  • The web based version of Google Earth as well as the desktop versions work great and you can manipulate the data however you like.
  • You can download the related KML/KMZ file from each of the eight special event station landing pages to see how they did.

A few things worth commenting on:
  • We used the 4 digit grid square locator, so all contact locations are approximate on the map.
  • To keep all data uniform, even our eight special event station locations on the map are approximate since we used four digit grids for them also, but actual locations are listed on the event website.
  • Grid square locations are listed in the center of each grid versus actual location.
  • Next year, we are going to try and ask for six digit grids instead of four digit for enhanced accuracy.

Please also take a moment to visit each of the sponsoring clubs websites to see what else they are involved in as we strive to continue to put the Hudson Valley and our amateur radio community on the map both figuratively and geographically!  

And, if you live in the Hudson Valley and interested in joining a club, here is a great way to learn more about nine of them through this great event.

Much more to follow.....

Operating as N2B, Steve K2GOG (Front, left) operating on 2m FM before a satellite pass.  Joe NE2Z using FT8 on 17m and Lloyd K2JVX in background on 20m SSB.

The Bannerman Castle Tour's were full of young and old that were interested in history.  Mark WA2NYY doing CW all the way at the back with Steve K2GOG and Joe NE2Z trying to be quiet during the tour presentation. Benefits of being a CW operator.....

Tuesday, July 6, 2021

L-Band: Frequencies You Need To Know About

L Band is defined by IEEE as 1 to 2 GHz and there is a lot going on in this valuable chunk of spectrum that will be of interest to any radio hobbyist, regardless if you are an amateur radio person or not.

In the United States, the Federal Communications Commission (FCC) visualizes L-Band like this:

Lets take a quick look at what to expect via some easy to monitor targets as single discrete frequencies:

  1. 1030 MHz ( ADS-B Interrogator)
  2. 1090 MHz (ADS-B/1090ES)
  3. 1176.45 MHz (GPS L5 & GLONASS L5OCM & Baidou B2a  & NavIC L5)
  4. 1191.795 MHz (Baidou B2a/B2b)
  5. 1202.025 MHz (GLONASS L3OC)
  6. 1207.14 (GLONASS L3OCM  & Baidou B2I/B2Q)
  7. 1227.60 (GPS L2)
  8. 1246 MHz (GLONASS L2)
  9. 1248.06 MHz (GLONASS L2OC & L2SC)
  10. 1268.52 MHz (Baidou B3I/B3Q/B3A)
  11. 1294.0 MHz (Amateur Region 3 FM Calling)
  12. 1294.5 MHz (Amateur Region 2 FM Calling)
  13. 1296.1 MHz (Amateur Region 2 CW/SSB Calling
  14. 1296.2 MHz (Amateur Region 1 CW/SSB Calling
  15. 1297.5 MHz (Amateur Region 1 FM Calling)
  16. 1381.05 (GPS L3)
  17. 1420 MHz (Hydrogen Line)
  18. 1544.5 MHz (COSPAT-SARSAT)
  19. 1561.098 MHz (Baidou B1Q)
  20. 1575.420 MHz (GPS L1 & GLONASS L1OCM  & Baidou B1C/B1/B1A)
  21. 1600.995 MHz (GLONASS L1OC & L1SC)
  22. 1602 MHz (GLONASS L1)
  23. 1691.0 MHz (GOES-10 WEFAX & MeteoSat & GMS)
  24. 1685.7 MHz (GOES-10 GVAR PDUS  & GOES-12 GVAR PDUS)
  25. 1694.1 MHz (GOES-16 HRIT/EMWIN & GOES-17 HRIT/EMWIN)
  26. 1698 MHz (NOAA-16 HRPT & NOAA-12 HRPT)
  27. 1702.5 MHz (NOAA-15 HRPT)
  28. 1707 MHz (NOAA-17 HRPT & NOAA-14 HRPT)

There is much more more beyond the above list worth looking at, but to do so, you need the right receiver and the right antenna to get started.

Your first L-Band Receiver

This is the easiest part to buy, but will get more complicated later on.  

Purchasing an inexpensive software defined radio USB dongle like a genuine RTL-SDR v3 will offer the most flexibility to experiment with for L-Band monitoring. Why?

  • Costs less than $40 USD
  • Can be repurposed for monitoring frequencies outside of L-Band
  • Can resolve signals up to and between 2.4 MHz and 3.2 MHz bandwidth
  • Relatively stable accuracy across entire tuning range thanks to its 1 PPM TCXO
  • Has a low power DC bias injector needed for some external amplifiers or antennae
  • Easy to locate closer to antenna or computer depending on application because of its USB and SMA connectors.

Many of the signals found in L-Band are data communications versus voice modes like N-FM or SSB, so using an SDR is the best way to get started.

Your first L-Band Antennae

This is a tough thing to address since an antenna at L band frequencies will have different benefits or shortcomings depending on what you wish to monitor.

With most applications for L Band focused on directional or space based communications, a pre amplified or passive patch antenna is a good way to start out as well as to try a single plane Yagi antenna.

Currently my "favorite" antenna for a large and interesting portion of L Band is made by the same folks who make the popular RTL-SDR V3 USB device mentioned above.  

Covering 1525 to 1660 MHz, this amplified antenna is very nice and comes with a length of cable and mounting options. Purchase direct from or via Amazon here.

While the nice suction and gripper base are included with the antenna, I found them personally a little annoying so instead for portable demonstrations, I am using this inexpensive tripod that extends up to almost 4ft tall and collapses down very small. And, it comes with some other accessories that made it an even better deal. 

There are many other options for specific portions of  L Band to consider especially if you are interested in ADS-B aircraft signals at 1090 MHz or the amateur radio portion of the band from 1240 to 1300 MHz but we are not going to focus on those in this article. 

Your first L-Band Software

There are so many options, but here is a list of the top options worth having on hand.

General Purpose:  SDRangel - This great and under appreciated software offers a lot if you are interested in L-Band monitoring. Built in mapping for ADS-B at 1090 MHz plus some helpful satellite prediction and visualization tools along with digital television options are a few examples. 

SAR & Navigation: Tekmanoid EGC/LES STD-C Decoder - If you are interested in decoding InMarSat satellites which are used for maritime shipping and safety along with some aircraft or search and rescue situations, this may be of interest.

High Resolution Weather:  XHRPT, HRPT Reader, HRPT Decoder for HRPT as well as GOES imaging are a few options ranging from free to paid software. 

There are enough videos and articles elsewhere that talk about how to set up this high resolution weather decoding using the 1.6 GHz range spectrum within L Band. Many people find success with repurposing  2.4 GHz Wi-Fi grid antennae with a simple modification or a purpose made 1.7 GHz version. 

HRPT satellite   HRPT satellite

Amateur DATV:  SDRangel - This program is great for many reasons, but one area to use it for is decoding different analog and digital video signals. A typical DVB-S2 signal is less than 300 kHz wide and using the 23cm amateur band using a Lime SDR or HackRF is a great way to experiment along with DATVexpess to transmit with, and use SDRangel to receive.


This article is not meant to be an exhaustive how to article, but to raise awareness of L Band and for the amateur radio crowd, to see how in demand this spectrum is and to find ways to utilize the 1240 to 1300 MHz allocation in the United States before commercial services further try to purchase this spectrum. 

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