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The Realtek 2832U

In my spare time (lol!) I have been fooling around with one of those RTL 2832U dongles and a bit of software.? For those that don’t know, the RTL 2832U is a COFDM demodulator chip designed to work with a USB dongle.? When coupled with an R 820T tuner a broadband RF receiver is created? There are many very inexpensive versions of these devices available on Amazon, eBay and other such places. The beauty of these things is that for around $12-30 and a bit of free software, one can have a very versatile 10 KHz to 1.7 GHz receiver.? There are several good software packages for Windoze, Linux and OSX.

The one I recommend for beginners is called SDR-Sharp or SDR#.? It has a very easy learning curve and there is lots of documentation available on line.? There are also several worth while plugins for scanning, trunking, decoding, etc.? At a minimum, the SDR software should have a spectrum analyzer, water fall display and ability to record audio and baseband PCM from the IF stage of the radio.

Some fun things to do; look at the output of my reverse registering smart (electric) meter (or my neighbor’s meter), ACARS data for the various aircraft flying overhead, a few trips through the EZPass toll lanes, some poking around on the VHF hi-band, etc.? I also began to think of Broadcast Engineering applications and a surprising number of things came to mind:

  • Using the scanner to look for open 950 MHz STL frequencies
  • Inexpensive portable FM receiver with RDS output for radio stations
  • Inexpensive Radio Direction Finder with a directional antenna
  • Inexpensive Satellite Aiming tool

Using SDR sharp and a NooElec NESDR Mini+ dongle, I made several scans of the 945-952 STL band in a few of our markets.? Using the scanner and frequency search plugin, the SDR software very quickly identified all of the in use frequencies.? One can also look at the frequency span in the spectrum analyzer, but this takes a lot of processing power.? The scanner plugin makes this easier and can be automated.

950 MHz STL frequencies, Albany, NY

Analog and digital 950 MHz STL frequencies, Albany, NY

I also listened to the analog STLs in FM Wideband mode.? Several stations are injecting their RDS data at the studio.? There is one that appears to be -1500 Hz off frequency.? I’ll let them know.

Next, I have found it beneficial just to keep the dongle and a small antenna in my laptop bag.? Setting up a new RDS subcarrier; with the dongle and SDR# one can quickly and easily check for errors.? Tracking down one of those nasty pirates; a laptop with a directional antenna will make quick work.

Something that I found interesting is the water fall display for the PPM encoded stations:

WPDH using RTL 2832U and SDR Sharp

WPDH using RTL 2832U and SDR Sharp

Not only can you see the water marking on the main channel, you can also see the HD Radio carriers +/- 200 KHz from the carrier frequency.? That is pretty much twice the bandwidth allotment for an FM station.

WDPA using RTL 2831U with SDR Sharp

WDPA using RTL 2831U and? SDR Sharp

Those two stations are simulcasting.? WPDA is not using Nielson PPM nor HD Radio technology.? There is all sorts of interesting information that can be gleaned from one of these units.

Aiming a satellite dish at AMC-8 can be a bit challenging.? That part of the sky is pretty crowed, as it turns out.? Dish pointer is a good general reference (www.dishpointer.com) and the Dish Align app for iOS works well.? But for peaking a dish, the RTL 2832 dongle makes it easy to find the correct satellite and optimize the transponder polarization.? Each satellite has Horizontal and Vertical beacons.? These vary slightly in frequency, thus, but tuning to the correct beacon frequency, you can be assured that you are on the right satellite.? All of the radio network programming on AMC-8 is on vertically polarized transponders, therefore,? the vertical beacons are of interest.? Here are the vertical beacons for satellites in that part of the sky:

Satellite Position C band Vertical beacon (MHz) L band (LNB) Vertcial beacon (MHz) Comment
AMC-8 139W 4199.5 949.25
AMC-7 137W 3700.5 1450.25
GOES15 135.4W 2209.086 N/A NOAA WX
AMC-10 135W 4199.5 949.25
Galaxy 15 133W 4198 949.00
AMC-11 131W 4199.5 949.25
Galaxy 12 129W 3700.5 1450.25

For those in the continental United States, there is not much else past 139W, so AMC-8 will be the western most satellite your dish can see.? Of course, this can be used in other parts of the world as well, with the correct information. Bringing a laptop or Windows tablet to the satellite dish might be easier than trying to drag a XDS satellite receiver out.

AMC8 vertical beacon output from LNB

AMC8 vertical beacon output from LNB

In order to use the RTL-2832U, simply split the output of a powered LNB, install a 20-30 dB pad in between the splitter and the dongle.? Using the vertical beacon on 949.25 MHz, adjust for maximum signal.

Some other uses; look for the nearest and best NOAA Weather radio station.? Several times the local NOAA weather station has been off the air for an extended period of time.? Sometimes, another station can be found in the same forecast area.? Heck, couple these things to a Raspberry Pi or Beaglebone black and a really nifty EAS receiver is created for NOAA and broadcast FM.? One that perhaps, can issue an alarm if the RSL drops below a certain threshold.

I am sure there are plenty of other uses that I am not thinking of right now…

Three generations of emergency communications

Even before CONELRAD was introduced in 1951, radio broadcasting was a critical part of the emergency communications infrastructure.? The government recognized early on the ability of radio to transmit data and information quickly, over large areas to the general public.? It works when all other systems fail, as demonstrated repeatedly over the years, the last of which occurred during Hurricane Sandy last October.? Massive destruction from flooding in lower Manhattan and shore side Brooklyn rendered the electrical grid, telephone network, the cellular network and the internet out of order.? Fortunately, enough radio stations stayed on the air and people used battery powered AM and FM receivers to obtain information.

CONELRAD poster, circa 1950's

CONELRAD poster, circa 1950’s

CONELRAD served two purposes; first, radio stations either re-tuned their transmitters to 640 or 1240 KHz or switched off the air. Then, each station that was still on the air would transmit for ten minutes, after which, they turned off and the next station in the chain would turn on and transmit for ten minutes. This was designed to confuse the Soviet bombers flying over the north pole on their way to incinerate us. Secondly, the CONELRAD stations were to distribute emergency information during and after said attack.

CONELRAD receiver

CONELRAD receiver

Recently, I found this CONELRAD receiver in a bomb shelter at a radio station. It dates to pre 1963, which is when CONELRAD was replaced by EBS.

EBS encoder/decoder

EBS encoder/decoder

EBS or the Emergency Broadcast System was a refinement of CONELRAD in several areas.? EBS used a two tone attention signal to unmute receivers and alert the public that something important may be happening.? Initially designed as a national system to warn of an impending attack, in later years it was also used by state and local governments to warn of other emergencies like weather, etc.

The current system is EAS or Emergency Alert System.

CAP compliant EAS

CAP compliant EAS

The Emergency Alert System was an advancement of the EBS in several areas.? Using SAME protocol in the message headers allowed stations to automate alert message relays.? This was driven by the desire for unattended operation.? The use of SAME also allowed many different types of messages to be filtered by alert type and area.? Each EAS unit also had an internal voice recorder.? All of this was upgraded in 2011 with the introduction of CAP, which would take email messages and generate computer voice alerts to be sent out over the broadcast stations.

Three generations of emergency communications equipment found at one facility.

The main problem with EAS CAP is it violates the engineering principle of KISS (Keep It Simple, Stupid).? It is an overly complicated system that relies on the internet, e-mail servers, the public telephone system and other infrastructure that may not survive natural or man made disasters, enemy attack or other disruptions.? Even something as simple as a national test proved to be problematic in 2011.

For a real emergency information network, the idea of WGU-20 has some merit.? Two or more well positioned medium to high powered LF stations could serve as a PEP distribution network and reliably cover the entire country.? With such a system, every broadcast station, cable head end and NOAA radio transmitter could monitor the LF stations directly, thus replacing most of the over the air daisy chain and or FEMA leased lines.? The advantages of LF is that it is fairly immune to HEMP, it goes a long way reliably, can have multiple redundant transmitter sites located within secure areas like military bases and uses time proven technology.? That would be a real, cold war solution.? But no, let us instead rely on a hodge podge of ISPs, TELCO leased lines, 3/4G wireless networks, SMS, satellite links, e-mail servers and the like, because: Hey!? It’s the digital age, we don’t need none of that stinking broadcasting crap.

EAS CAP deadline approaching, some things to keep in mind

There is something like two weeks left until the deadline for installing CAP compliant EAS equipment.? No, this time they really mean it!


I have installed a few of the new SAGE ENDEC boxes at various clients. They do have one common problem; audio input levels. The newer blue faced SAGE units are much more sensitive than the older units. The existing audio input levels connected to older EAS units need to be adjusted downward nearly 100% of the time.? SAGE Alerting Systems has a bulletin about it: SAGE Alerting Systems Audio Levels.

In addition to that, SAGE Alerting Systems has released CAP compliant firmware, available at: Updates for digital SAGE ENDEC


EAS text to speech permitted, not required

The FCC reverses it’s former position on EAS text to speech, permitting stations to begin using it today (May 7, 2012).? The FCC’s main issue with Text To Speech (TTS) was that it may? not render the text accurately enough to be understood, especially in emergencies.? This can lead to confusing messages and defeat the purpose of EAS altogether.

I have played around with some text to speech software and indeed it can mangle words, mispronounce punctuation as a part of the sentence structure, mumble, etc.? Further, as I have said before, listening to some robo voice is very impersonal.? But, I suppose that is the point, isn’t it; some big government agency computers generating messages that no one person is really responsible for.? Bureaucratic paradise.

National EAS test results

Mixed, at least in my neck of the woods. ?I was stationed at a LP-1 station which was monitoring a PEP station directly. ?On my end, the test went fine without intervention. Please excuse the cellphone video, I am used to my good camera, which I left at home.

Many others in the New York area had problems. ?Stations with newer SAGE (Blue front) CAP capable EAS ENDECS had issues, even the ones that were also monitoring the PEP stations directly.

Many of those stations broadcast the header tones and about 10 seconds of audio. ?The audio abruptly stops and is followed by twenty seconds of dead air followed by the EOM. ?I can speculate that the SAGE EAS units should be checked for proper configuration and be tested back to back while receiving duplicate messages from different sources spaced apart by ten seconds.

Several stations downstream from the LP-1 stations did not receive anything at all. ?Others received the alert tones but no audio, some had high levels of background noise, thirty seconds of static, audio cut off, etc. ?All in all, most would look at this and say “Thank God it wasn’t a real emergency.” ?Silver lining: For all those that are concerned that the federal government will attempt to diabolically take over the entire broadcast spectrum and say evil things; Doh! foiled again.

National EAS Test

Video available by youtube, courtesy of Radio Magazine:

It is a pretty good simulation of what will happen on November 9th. ? The script used is not the actual script that will be used for the national test.

After the test, the video shows how to bail out of the national test in the event that a valid EAN is not received. ?This is important information, as this particular failure has occurred many times in the past. ?If the LP-1 or PEP station that transmitted the test fails to send a valid EOM, the EAS unit will continue to transmit that station’s programming indefinitely. ?If the LP-1 or PEP station resumes regular programming while the EAS unit is relaying their programming over the air, that would be a good indication that the LP-1 or PEP station has failed to send a valid EOM.

Update: Paper work is required.

Less than one month until the Coordinated National EAS test

November 9, 2011 at 2pm EST, FEMA will be testing EAS with it’s first ever national level test. ?To promote that event, they have released a twenty eight page “tool kit,” (near the bottom of the page) designed to help everyone get through the test. ?It should be interesting. ?According to FEMA:

The nationwide EAS Test is not a pass or fail measure, nor will it specifically test Common Alerting Protocol (CAP) compliant equipment (although CAP compliant equipment should pass the Emergency Action Notification [EAN] live-code in the same manner as legacy EAS equipment).

They will release a Emergency Action Notification (EAN) to all the Primary Entry Point (PEP) stations, which should then flow down stream through all the radio, television, cable systems, and direct broadcast satellite systems. ?The test should last about two minutes and will conclude with a standard EOM.

I doubt very much it will sound like this:

That is WHEN, Syracuse, NY singing EBS test. ?A bit of originality there. WHEN played this for their weekly EBS test for the better part of the 70’s. ?Naturally, the FCC found out about it and told them to stop. ?Shame, really, it is kind of catchy.

If you have some spare time, download the tool kit and study up for the test.

The Nationwide Coordinated EAS test

This is a test, you have been warned. ?The FCC has scheduled the first nationwide mandatory EAS test for November 9th, 2011 at 2pm EST (1900 UTC). ?According to James A. Barnett, Jr., Chief, Public Safety and Homeland Security Bureau:

For the test, FEMA will trigger the EAS “cascade” architecture by transmitting the EAS code used for national level emergencies to the first level of broadcast stations in the national-level of the EAS, which in turn will rebroadcast the alert to the general public, as well as to the next level of EAS participants monitoring them. This should continue through all levels of the system until the alert has been distributed throughout the entire county.

Since this date is beyond the CAP deadline of September 30, 2011, it seems like CAP would be the distribution method, but there is not anything I can find to verify that. ?The above paragraph makes it sound like the PEP system might be used.

This will be an interesting evolution for a number of reasons. ?If the EAS system fails operate as planned after giving five months warning for a nationwide test, it would point toward a fundamental design flaw in the system. ?A more realistic test of the EAS system would involve perhaps one hours notice and then trigger the event. ?Notice should be given so that broadcast station personal can answer questions from the listening and viewing public.

Then there is the EAS ?EAN protocol itself. ?There are many that feel, rightly or wrongly, that the federal government should not be able to take control of privately owned broadcast stations and cable systems for any reason. ?The way that the EAS encoder/decoder units are now required to be wired into the audio air chain means it would be very hard to override any mandatory alert, such as an EAN, if there were a reason to do that. ?There have been several instances of false alerts, WGN-AM being the most recent, where programming on down stream broadcast and cable systems were disrupted for several minutes.

So, save the date. ?It will no doubt be interesting to see how this all works.

ให้ เงิน เล่น ฟรีEAS/CAP continued

Lots of ink has been spilled about the new CAP (Common Alert Protocol) implementation and what it all means. ?Since the FCC started the six month CAP clock ticking on September 30th of last year, they have extended the deadline by six months to September 30, 2011.

The idea of upgrading EAS is a good one. ?When EAS replaced EBS in 1997 it was supposed to do away with the over the air relay system also known as the daisy chain. ?This was left over from the 1960’s CONELRAD system implemented by Kennedy. ?That replacement never occurred and stations today are still monitoring other broadcasting stations for their EAS alerts. ?The daisy chain was and still is the source of all EBS and EAS failures.

CAP is supposed to eliminate that weak link by allowing the EAS unit to access government IPAWS message servers directly, allowing FEMA to automatically send out alert messages to designated areas. ?This has some libertarians in an uproar, as they see government intrusion and taking over privately owned radio stations to broadcast emergency information as a form of tyranny. ? In as much as the definition of “emergency message” has not been codified by FEMA in any of their information, they may have a point. ?In the past, the general definition of emergency communications were those that were pertaining to imminent threats to the safety of life and property. ?According to Executive Order 13407, Public Alert and Warning System, the purpose is to:

…have an effective, reliable,?integrated, flexible, and comprehensive system to alert and warn the American people?in situations of war, terrorist attack, natural?disaster, or other hazards to public safety and?well-being…

Which is certainly much ?more broad in scope. ?How does one define a hazard to “well-being?”

SAGE alerting systems have completely revamped their ENDEC to include CAP 1.2. ?It uses the internet to connect to IPAWS servers and receive CAP messages. ?As the SAGE ENDEC owners manual notes, participation in local and state level alerts are at the discretion of the station management, as regulated by the current version of FCC Part 11. ?National level participation is manditory:

Participation at the national level is mandatory for most broadcasters. ?You may petition the FCC to become?a “Non Participating National” station, but you must still receive and broadcast the EAN code, and then?leave the air. ?These requirements are always evolving, refer to the FCC rules, in particular CFR 47 Part 11?for details.

Often times, it is the local emergencies that are greatest and most immediate threats to human life; the tornado, the tsunami, etc. ?Those are the most pressing threats, not the national level alerts, which were implemented ?in the 1960’s to warn of a major attack from a foreign country, something not very likely these days.



Further, the internet has proved to be less than reliable when trouble occurs. ?During the terrorist attacks on 9/11/2001, dial tone, cellphone and internet service for much of lower Manhattan were disrupted because the TELCO facilities were in the buildings that were destroyed. ?Most internet services rely on wired or fiber optic services provided by TELCO or cable company, which can be effected by power outages, damaged infrastructure and so on, which would likely occur in a major emergency.

It does not seem to be the most robust method for distribution of emergency messages.

Passive AM Monitor Antenna

At the place of my former employment, there is an issue with AM reception. The building is full of old, electrically noisy fluorescent light balasts, computers, mercury vapor parking lot lights, and every other electrical noise generator under the sun. ?The second issue is that one of the EAS monitor assignments for two FM class B stations is WABC in NYC. ?Under normal conditions, WABC puts a fine signal into the area. ?Listening to it is not problem at my house, in the car and what not. ?However, at the studio the station is audible, but terribly noisy. ?Every time one of those FM stations ?ran a required monthly EAS test originated from WABC, it was full of static and just sounded bad on the air.

The state EAS folks were inflexible as to the monitoring assignment. ?“WABC is the PEP station for NY. ?You should have plenty of signal from WABC at your location,” said they.

At one time, the studio had an active loop antenna (LP-1A) from Belar, which worked, but also seemed to amplify the noise. ?I decided that the best thing to do was go big and ditch the preamp. ?I made a diamond shaped receiving loop on two pieces of two by four by eight foot lumber. ?I wound four turns of #14 stranded wire around this frame and made a 4:1 balun to feed the unbalanced 75 ohm RG-6 coax.

That cured the noise problems and for eight years, WABC sounded pretty good on the EAS monitor.

Fast forward to about a week ago. ?The roof at the studio building was being redone and all the monitor antennas had to be removed from the roof. ?The homemade loop was not in good shape. ?The balun box was full of water, the lumber was cracking and falling apart, the insulation was degraded by UV exposure, etc. ?My boss asked, “how much to make a new one?” ?So I said something like forty dollars and a couple of hours. ?He then said, “Make it so we don’t have to ever make another one.”

Music to my ears. ?I started by checking my assumptions. ?I made a model and ran NEC to see what the electrical characteristics for that size loop were on 770 KHz. ? It came out better than I thought, about 1 ohm resistance and 282 ohms inductive reactance. ?Fooling around a little more showed that roughly 1.3 uH inductance and 720 pF capacitance in a L network would bring this inline for a 50 ohm feed point. ?Since this is a receive only antenna, that is not a prime consideration. ?I am more concerned with noise reduction and maintaining at least the bi-directional quality of a loop antenna.

NEC 2 model AM receive loop

NEC 2 model AM receive loop

Then, I decided to get fancy. ?What if the capacitance was put on the end of the loop to ground instead of the feed point. ?That, in effect should make the loop directional off of the unterminated side. ?Driving the feed point with a 9:1 balun would also bring up the inductance on the feed point. ?Finally, grounding the whole thing with a separate ground lead might also get rid of some noise.

The final configuration looks something like this, which is essentially a top loaded vertical:

Low noise AM loop antenna

Low noise AM loop antenna

Now to build it.

Once again, I felt that a non-conductive support was needed, so I used two by four by eight foot lumber, but this time I painted them with oil based paint. ?The side length worked out to be 5.7 feet per side, or 23 feet per turn for a total of 92 feet of wire.

I purchased 100 feet of PV (photovoltaic) wire (Alpha wire PV-1400), which is UV, heat, moisture resistant and designed to last for 30 years in outdoor, exposed environments.

For the balun box, I used a metal outdoor electrical box with a metal cover. ?I put a ground wire jumper between the box cover and the ground common to maintain shielding. ?I used a water tight bushing to feed the antenna wires and the ground wire into the box. ?I drilled a 3/8 hole for a type F chassis connector. ?Everything was given a little extra water proofing with some silicone based (RTV) sealant on all threaded junctions.

The spreaders for the wire windings are UV resistant 1 inch PVC conduit. ?I drilled four holes, three inches apart in each spreader to run the loop wires through.

The balun is 7 trifiler turn of 24 AWG copper wire on an FT-43-102 toroid core. ?Trifiler means three wires twisted together before winding the toroid core.

I used all stainless steal screws and mounting hardware.

The loop is terminated with a 500 pF, 500 volt ceramic capacitor to ground. ?Once in place, I am going to experiment with this by jumping it out of the circuit to see what effect it has on noise and signal strength. ?I may also try replacing it with a 200 ohm resistor and or a 1000 pF capacitor.

The assembly was pretty easy, although time consuming. ?My four year old son helped me paint the wood and string the wires through the spreaders.

I soldered all wire connections with 5% silver bearing solder.

When the whole thing was assembled, I tested it out with my Drake R8 receiver. ?It performs much as expected, low noise, directional away from the terminated wire loop. ?It does not appear to be too narrow banded either, as the stations on the high end of the dial were also received with good signal strength.

Next was loading it on the pickup truck, driving it in and mounting it on the studio building. ?I got some funny looks from my fellow travelers, then again, I usually do.

For the ground, I purchased an eight foot copper clad grounding rod and pounded it into the ground at the corner of the building. ?This area is always wet as it is the lowest area around the building and all the gutters drain there. ?This is not be best RF ground, but for the purposes of this antenna, it should work fine. ?I used about 28 feet of left over #12 stranded wire from the ground rod up to the balun box and connected it to the common ground point inside the box.

The frame itself is mounted on a standard wall mount antenna pole. ?Stainless steel clamps hold the wood frame to the pole.

Once it was installed, I used my Kenwood R-2000 receiver to find the best mounting azimuth and locked everything down. ?I also put a toroid on the RG-6 coax coming up from the rack room to keep any shield noise from getting into the antenna.

AM receive loop PVC wire spacers

AM receive loop PVC wire spacers

AM receive loop wood frame

AM receive loop wood frame

AM receive loop balun transformer

AM receive loop balun transformer

The tuning capacitor is in there too, behind one of the loop wires.

AM loop antenna installed on roof

AM loop antenna installed on roof

Antenna installed. ?I did try substituting the 500 pF capacitor with a 220 resistor. ?The signal strength came up somewhat, but the noise increased more, therefore the capacitor is a good termination for this antenna.

With this antenna, the signal from WABC is nice and clean and sound good on the FM station when a monthly EAS test is retransmitted.


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19

...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

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