Wednesday, November 15, 2017

Using a Software Defined Radio (SDR) on the FM Broadcast Band to Foretell 2-Meter Band Openings


Background

    I have always enjoyed the DX’ing hobby. It started for me during the Fall/Winter of 1961-62 when I suddenly started hearing “Clear Channel” AM Broadcast stations on a 6-Transistor radio. Then living in Houston, Texas it wasn’t too uncommon to see a central, south or southeast Texas TV station on our Rabbit-Ears sitting on top of the Black & White television.
    In the early 70’s, I put up a good outdoor log-periodic VHF/UHF-TV/FMBC antenna, a Citizens Band 4-element Yagi and a rotor to turn it.  My DX’ing focus changed from medium and short waves to the higher frequencies (11 Meters, VHF and UHF).  Besides living in Tropo Heaven (Houston), I started to experience some great Sporadic Es on TV Channels 3-7 and correlated it to activity on CB and Ham Radio 10-Meters.
    In 1978, I had moved to Fort Worth, Texas and by 1979 finally became a Ham. Of course, 10 Meters was my favorite HF band.  A few years later (1982), an interest in Amateur Radio satellites helped me acquire an all-mode 2-Meter transceiver. Once I worked a couple of Tropo openings and my first 2-Meter Es opening, everything in my Ham Radio life changed.
    I put back up the V/U/FM Log-Periodic and hooked it up to my old 13 inch Black/White Zenith TV (used as a monitor for my Timex/Sinclair Satellite Tracking computer). I actively began monitoring TV reception to use it as a tool to gage whether a 2-Meter DX event was going to occur. I also started using my car/truck radio to monitor the FM Broadcast Band.  Later on, I added a 4-inch B/W TV to the truck attached to my 5/8 wave 2-Meter vertical whenever I travelled.
    I was able to correlate events on Lower Channel TV and FMBC to Es openings on 2-Meters.  I could operate 10 & 6-Meters and look for shortened paths, including backscatter.  I could also observe TV and/or listen to FM and do my best to identify what I was seeing or hearing.  After a few openings, I learned that if I saw and identified a Channel 6 TV station or a FM station on Sporadic Es, if 2-Meters opened, it was to that same general area of the TV or FM station.  A few times, exactly to the place I monitored.  I used it to my advantage. For most of the first 5 years on 2-Meter SSB and again for a short term in 1990-91, I ran 30 watts out on 2-Meter SSB.
    Most good things sadly come to an end.  Living in Dallas/Fort Worth area, I saw it grow from 3 to 6.5 million people. So did the number of FM broadcasters multiply over that period.  A number of outlying town’s FM stations expanded their coverage.  Before, the vast majority of transmission towers were located to my south-south-east. A few new ones were now to my northeast. The final insult was the local PBS affiliate (KERA) pulled out an old approved license for TV Channel 2 (UNT or N. Texas State) and killed that frequency for monitoring.  Channels 2, 4, 5, and 8 were now occupied locally. KERA-2 was a failure and sold it to a Gospel of Wealth religious organization.  In the end, HDTV took over and most stations moved to UHF.
    I took a hiatus from VHF/UHF DX’ing from 2008-14, pulled down the tower and antennas, retired in 2014 and moved to the upper desert of Arizona.  I set up shop in Arizona by the beginning of 2015 and starting working on new VUCC’s.

Now in Arizona
    Unfortunately, I moved here towards the second peak of Solar Cycle 24.  Despite what others tell you, this solar cycle had an adverse affect on VHF propagation. 2 Meter Es openings have been far and few between. 6-Meters has had good moments from time to time, but has not had a long period opening (24 hours) in many years. 2015 was okay, 2016 was a bit of a stinker season and finally 2017 has seen a very good improvement despite a few quiet periods.
    Trying to work VHF Es can be challenging at times here in Arizona. The best distance for single hop Es tend to be in low Ham Weak-Signal populated Grid Squares. Timing to populated Grids has been way off so far. Much of my Es DX has actually been Double-Hop Es. This year, my average distance for a 10-Meter Es PropNET capture (1,883) was 300 kilometers longer than the next closest average participant. Of all the major PropNET participants (23), my captures were 500 kilometers longer than the overall average (1,348).
    For quite a number of years (late 90’s) on the Internet, I had visited DX World operated by Bob Colyard of New Jersey (www.dxworld.com). Bob had set up various lists for the DX enthusiasts. Hams from HF to UHF, special modes, and SWL’s all had a List to post their latest DX accomplishments. I have reported many a 2-Meter Es, Tropo and Aurora opening, as well as 6-Meter Es and F2 openings before reporting to other sites such as DXSummit, DXScape and DXMaps became more common. Thanks to well known VHF DXer Pat Dyer - WA5IYX, the TV/FM Skip Log ( http://dxworld.com/tvfmlog.html ) became a popular place to share various VHF and UHF propagation events.  The genius that Pat was also led to many a discussion about Es.  I used it from time to time to gauge what was happening on VHF and once I moved to Arizona, I shared with the others what I was observing here.
    Once analog TV ended in the U.S., followed by Mexico and dwindling in Canada, the Logger was concentrating more on FM Broadcast Band DX.  I felt a little disadvantaged here.  I can DX with the best of them, but other than my radio in my car I did not have a receiver that could decode FMBC RDS and PI Codes. When you are working DX on 6-Meters and trying to raise 2-Meters from the dead, it is a little tough trying to identify FMBC stations when your attention is on other matters.

Looking For Solutions
    Software Defined Radio has really made its presence known the past few years. Technology works wonders. It has happened so fast, I haven’t been able to keep up. I had seen advertisements for a number of devices ranging from $150 to $450.  Being retired and wanting to put my money behind more beneficial things such as Ham Radio, I really didn’t want to spend a lot of bucks on something used a little.  Hams are notorious for spending themselves into debt for things they don’t use or get that much out of.  I have always done my best to squeeze blood out of a turnip.
    Towards the end of the 2016 Spring/Summer Es Season, I looked for a SDR on Amazon. Cookies got me and started seeing ads for them whenever I visited a website that allowed cookies.  Shortly after, I saw an ad for a RTL-SDR for $17. What did I have to lose?  I purchased a couple of other items I needed to get free shipping (the wife refuses to join Prime).  A few days later I had the RTL-SDR.


    Instructions for these devices are a little short, but if you are a tech-nerd you figure it out. I had 4 old computers (two XP, one Vista, and one Windows 7) and quickly found out that the Windows 7 laptop was the best computer to use.  I also had to order a couple of SMA feed-line connectors, one with a female F-Connector and one female BNC. As for software, SDRSharp was used when Windows 7 was the operating system. I liked the ability of picking up RDS and software that is free.
    I had a myriad of antennas to plug in and struggled with which ones to choose. I settled on a FM-Turnstile (crossed dipoles) about 20 feet up the tower and hoped for a high MUF before the Es season ended. Luckily, a high MUF occurred. I was absolutely stunned what I was picking up. It was a good late season Es opening (8/05) and nearly every FMBC frequency on the low end was active. I did pick up several Louisiana and Texas RDS call and slogan identifications. I never expected that result with a multi-directional antenna. I tried out the log-periodic, but by then conditions had deteriorated.
     I spent the fall and winter trying the SDR on other frequencies (Aviation) and several Ham bands, but I just got more enjoyment on FMBC.  I did acquire a refurbished Windows 7 Pro desktop to operate a computer to Ham Rig interface along with the RTL-SDR. I was active this year on 10-Meter PropNET (last year WSPR) and wanted the flexibility of doing my automatically controlled digital station and the SDR on the same computer. My Log-Periodic has an advantage over the turnstile with forward gain and being able to null out strong (semi)local stations.  
Two Dell Desktops. The RTL-SDR overwhelmed by cables.
45 year old Archer V/U/FM-125 Log Periodic (UHF elements removed). 
A FM Turnstile (omni-directional) antenna is mounted about halfway up the tower.
    As Radio Shack was closing, I picked up a higher quality Antenna/Cable switch for both FM/TV antennas and placed it behind the desktop computer where the RTL-SDR was placed.  With a lot going on in my personal life and little time, I got it together as best I could for the 2017 Spring/Summer Es season.

Editorial Comment
    First of all, there are a number of excellent devices, and I would expect by the cost of these that they will outperform the RTL-SDR.  In addition, there are a number of software packages at a cost that maximizes their capabilities.  I do this for one simple reason, to help give me an edge to maximize my goals and pursuits in Ham Radio Weak Signal activities. I place my attention and my fixed income finances on that first.
    This activity using the RTL-SDR comes secondary and does a support role.  I chose the RTL-SDR device because it was inexpensive, the SDR Sharp software because it was free and I already had the outdoor antennas in use for DXing over many years.

This can be done better, but I argue it can be done as well as cheap.☺



Location:
Dewey, Arizona east of Prescott in the Lonesome & Skull Valleys
Grid Square DM34un
Elevation 4720 feet



First FMBC Es Event – August 5, 2016
The RTL-SDR was plugged into my Windows 7 Toshiba Laptop and the FM Turnstile hooked up.
Four (semi)local FM stations are appearing. 93.9 Flagstaff @ 51 miles, 94.3 Chino Valley @25 miles, 94.7 Prescott @ 12 miles (behind a mountain peak) and 95.1 Sun City West @ 23 miles  & 41 kW.

This is what a quiet band looks like from my home in central Arizona.

The same spectrum shown on Steroids during a high MUF and intense Sporadic Es opening.
Identifying the Early Signs

Sporadic Es usually show up on 10-Meters first. The easiest way to detect them is to listen for CW beacons between 28.2 and 28.3 MHz. Today’s new Ham tends to not copy CW very well. If so, use a computer to read them. There are real-time propagation reporters called CW Skimmers and show there spots on sites such as DXMaps. But unless you live close to a Skimmer, there is not much of a guarantee for your conditions. Active SSB chatter on the phone frequencies tends to show up later into the opening. Another way to know of 10-Meter openings is to capture PSK31 PropNET transmissions on 28.1186 MHz.  I have been active with them almost 15 years.

Once 10-Meters has been open consistently for around 15 minutes, you should be checking out 6-Meters. Like 10-Meters, there are a large number of beacons between 50.05 and 50.08 MHz. You can also listen to the SSB call frequency 50.125 MHz and up in frequency to 50.200.  A little troubling this year was a large increase in WSJT digital modes (FT-8 & MSK441). Yes it makes easier to DX QSO’s, but it really removes the excitement of exchanging a signal report, name and QTH by voice or CW. Once you notice that the path is getting shorter in distance then it is time to be watching for opportunities building to 2-Meters.

Here is where using this SDR device helps. One can visually see on the software spectrum to what Es are beginning to do.  First of all, be familiar to where local and semi-local stations are located. Use online sources such as FMFool.com, FCC FM Query or FMLIST.org.

I am blessed to be located in an area in which the major population centers (Phoenix & Tucson) are to my South to Southeast.  My VHF DX interests are in other directions. On this screen, the closest FM station (92.5) is weakened by hills and a mountain.  The others are 50-60 miles away.

Example of a normal FM Broadcast Band with no DX.
As the MUF of Sporadic Es increases, the incoming Es signal is full of rapid fading.  It is easily identified on the waterfall of the software, SDR#. The in and out fading signals appear as beads on a bracelet.
Weak Es signals begin to appear on 91.9, 92.7 and 93.3 MHz. A second signal is also appearing with local 92.5. This opening appears to have a small footprint.
Sometimes the beginning of an Es opening shows more opportunity. It might be a larger coverage footprint or a more populated area.






On these examples, nearly every FM channel is showing a growing Es opening.
If the Es opening continues to develop and intensify, the waterfall will show the resulting stronger signals.



The rapid fading conditions are still evident on strong signals.  Once signals approach 15 db above the noise floor, you have a good chance to decode RDS and PICode information.
Once you identify a FM broadcast station, begin to concentrate your 2-Meter efforts in the direction. My experience has been throughout the years that if and when 2-Meters opens, it will be in that direction and many times to the specific area you heard on FM broadcast.

A good sign in a FM Broadcast band Es opening is the stabilizing of conditions. Fading is less and the waterfall looks more like locals or Tropo. As the amplitude increases, it is time to see what the upper part of the FM band looks like.







These screen prints show a stable Es opening. Fading is much slower to non-existent.  It is time to look at the upper portion of the FMBC band and call on 2-Meters.
Looking at the lower end of the FMBC band (88-96 MHz) became addictive many times. Being the first year using a SDR, I was having so much fun watching it develop that I was ignoring the top part (104-108 MHz) of the band.




Once you see openings at the top part of the FMBC band, the chances of having Es conditions on 2-Meters really improves.  By now you should be sending CQ on 144.200 MHz and listening for others. Conditions here can help you be ready on 2-Meters.
Recognize and identify the FM stations as quickly as possible. Have a website, such as DXWorld-TVFM LogFMList or the Worldwide TV FM DX Association to help you narrow down the choices.
Once you identify a station, look for the distance between you and further identified stations becoming shorter in distance. This indicates a rising MUF. Once Es make it to 2-Meters, the chances are that it will be at the farther location you first identified.
Example: From here in Arizona, I hear and identify a Seattle WA FMBC station. Minutes later, I hear and identify a closer Portland OR FMBC station. The 2-Meter opening more than likely will occur around Seattle WA.


I cannot promise you great results, but I can assure you that being aware of these conditions and using these methods will improve your chances of working great distances on 2-Meter SSB next Es Season.


2017 Spring/Summer FM Broadcast Catches with the RTL-SDR

1 comment:

  1. Nice breakdown Art. Been using an RTL-SDR, but needed more and went for a higher priced SDR as a follow-on. I don't have the antenna array to work (just a multiband 6M-2M-.7cm vertical) with but have been occupied with some other pursuit like HF FMT. Keep up the great work. Glad to see you are alive and well.
    KD4IZ

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