Category Archives: FM

Activating mobile phone FM: FCC Chairman Ajit Pai’s remarks at NAB symposium

Many thanks to SWLing Post contributor, Aaron Kuhn, who shares the following:

FCC Chairman Ajit Pai’s remarks at the North American Broadcasters Association’s Future of Radio and Audio Symposium from today have been posted at

http://transition.fcc.gov/Daily_Releases/Daily_Business/2017/db0216/DOC-343529A1.pdf

I found the most interesting info in the statement is only 44% of the top selling smartphones in the US have an FM Chip activated have them activated. This figure pales in comparison to Mexico, where 80% of the top selling smartphones have the FM Radio chip activated.

Chair Pai goes on to state:

“You could make a case for activating chips on public safety grounds alone. The former head of our Federal Emergency Management Administration has spoken out in support of this proposal.

[…]I’ll keep speaking out about the benefits of activating FM chips. Having said that, as a believer in free markets and the rule of law, I cannot support a government mandate requiring activation of these chips. I don’t believe the FCC has the power to issue a mandate like that, and more generally I believe it’s best to sort this issue out in the marketplace. For despite the low numbers, we are seeing progress; in the last two years, the percentage of top-selling smartphones in the United States that have activated FM chips has risen from less than 25% to 44%. “

Which leads me to this question for the SWLing Post community: would the benefits, emergency and otherwise, of mandated, activated FM Receiver Chips in new Smartphones sold outweigh the free market arguments?

Feel free to share your comments!

Please note: our SWLing Post comment moderators keep this site a safe haven from partisan politics–after all, we’re here to talk and play radio! Sometimes, however, local/international politics and radio intersect, but please leave partisan discussions or any animosity for specific politicians for a political site. 🙂

FM Notch Filter for SDRPlay RSP1

RF filters are used (as the name implies) to filter/remove the frequencies you are not interested in and/or let frequencies you want pass . They come in lots of types. For example a band-pass filter lets the signals in a frequency range to pass through it and rejects/attenuates other frequencies. The opposite of band-pass filter is a band-reject or band-stop filter (also called a notch filter) which rejects/attenuates signals in a specific range and lets other frequencies get through the filter. Lots of different filters are used in SDRs and traditional radios. For example AM low-pass filters (only let frequencies lower than 1.7MHZ or so pass) or band-pass filters for various ham radio bands.

One of the popular use cases for a notch filter is in the FM broadcast range (88-108 MHZ in most parts of the world)

When you live near a powerful transmitter, it can affect the operation of your receiver in other near frequencies (or overload your receiver’s front-end), but I didn’t want the notch filter for this reason. I’ve got a SDRPlay RSP1 (among many other SDRs) which due to its architecture, has some images of FM band in the UHF range (for example in 330-350 MHZ). In fact they’re the images of the product of LO harmonics and FM frequencies.

You can temporarily move/shift the frequency by changing the LO frequency which does not remove them, but moves them around.

Another method to remove these images is using a band-stop filter.

This is the filter I’m using (Thanks to my friend Amirhosein Hasanpur who designed and built it):

Here you can see the effect of using a FM notch filter on my SDRPlay RSP1:

FM, without filter:

FM, with filter:

UHF (images) without filter:

UHF (images) with filter:

Here’s a link to a Zip file containing the PCB (in Protel), schematics (pdf) and S Parameters (pdf):

https://www.dropbox.com/s/l98kylrofohgqxf/SWLing.zip?dl=0

Note: Like any other SDR test/review, the results depend on lots of different parameters (various gain values, LNA, antenna, software, etc). These pictures are captured with the same conditions just to show the effectiveness of this filter and your milage will definitely vary, but expect a similar outcome. If you live close to a powerful transmitter or use LNAs, you will receive some signals, even when using the filter.

Final note: this issue is solved in the newer version of SDRPlay (RSP2) : it has software-selectable notch filters for FM and MW broadcast frequencies.

Mehdi Asgari, the author of this post, is a regular contributor to the SWLing Post. Mehdi lives in Tehran and is an active member of the EP2C amateur radio club.

Tecsun S-8800: Unboxing, photos, and initial impressions

Yesterday, I received a Tecsun S-8800 from Anon-Co in Hong Kong.

I like opening radio boxes to find a cardboard insert like this one. It protects the radio and has so much less waste and individual cardboard bits inside.

As I always do when a new radio comes on the scene, I requested to purchase an early release of the Tecsun S-8800 radio for review months ago.  But this time, my contact at the Chinese distributor Anon-Co, Anna, insisted on sending us one “as a gift for the Chinese New Year of the Rooster.”

Because I’ve worked with Anna at Anon-Co for at least a decade, having purchased numerous radios for review and as gifts for family and friends, this was difficult to refuse.  I decided there was no need to do so. Each time I do an in-depth review and note shortcomings or deficiencies in the radios I’ve purchased from Anon-Co, Anna immediately passes my feedback and criticisms directly to the manufacturer’s engineers. I believe this feedback loop between customers, reviewers and manufacturers leads to improved product iterations. Of course, sometimes the negatives can be so problematic, manufacturers simply drop the product line and move on (remember the Tecsun R-2010D?  Case in point). So, while there are a number of other eBay retailers in China that distribute Tecsun radios, I prefer Anon-Co for these reasons.

Thank you, Anna!

The S-8800 is packed face-down to protect the front panel.

Manufacturers and retailers who send me products for review know that we radio geeks have fairly high expectations of our gear, and will therefore hold them to exacting standards. I’m not the least among these.  While I endeavor to be realistic, understanding producers’ limitations and the need for product growth, I also try to keep my reviews as objective as I can, and accommodate my own and others’ particular requirements and preferences.

So In the spirit of full disclosure, I must note that I’m not as avid a user of large portables like the S-8800 (or the Grundig GS350DL, S450DLX, or the C.Crane CCRadio-SW).

Personally I prefer smaller, full-featured travel-friendly portables, or else larger tabletop models.  Radios with a form factor like the Tecsun S-8800 are an “in-between” product in my world, thus I rarely use them.

That said, every month I receive questions from readers looking for this very “large portable” form factor. Some hobbyists enjoy a radio that’s easy to operate, featuring simple controls, robust audio, and dedicated external antenna connections.  For these listeners, a large tuning knob and generous display are more important than things like SSB and synchronous detection.In other words, they want a broadcast receiver. Some have literally asked for a modern version of the venerable Panasonic RF-2200 (which I admittedly love, an exception to the rule of my avoidance of large portables). In terms of aesthetics, it’s impossible to live up the legendary solid-state RF-2200, in my opinion…kind of like comparing a modern muscle car with the 1960s original from which it copies its design.

The S-8800, and its many predecessors, were certainly influenced by the RF-2200’s popular design & form factor: large speaker on the left, large tuning knob, wide-spaced knobs, and a generous display. Like the RF-2200, it has a durable, adjustable woven carry strap.  

The S-8800 ships with the accessories in the photo below: an IR remote control, two rechargeable cells, an RF adapter, and a USB charging cable.

Note the charging cable is only a cable; the S-8800 doesn’t ship with a wall-wart type charger. If you’re like me, you probably have a handful of USB chargers scattered around your home that you could use for the purpose of charging this radio.  And if you don’t, you can also use any free USB port on your PC to charge it.

USB chargers are cheap and well-known to spew RFI. I doubt you’ll enjoy listening to shortwave or mediumwave/AM while charging the S-8800’s internal cells. It doesn’t appear the S-8800 was designed for listening while plugged in; Tecsun clearly wants you to charge it and then listen, off battery power. The latter is my preference for listening anyway, but it may put off some potential S-8800 owners.

The display is easy to read from any angle, and it’s also easy to view in bright sunlight. In low light, you’ll be pleased with the backlight function.

On the right side of the S-8800, you’ll find an internal/external antenna switch, a DX/local switch, RCA type stereo line-out ports (covered in the photo above) and a stereo headphone jack.

On the back, you’ll find a mini USB port for charging, an antenna port for a radiator and ground wire, as well as an FM antenna port. 

The battery cover is predictably located at the bottom of the back panel and––a first for any shortwave radio I’ve reviewed––accommodates two (supplied) 3.7V Li-Ion (internally) rechargeable cells.

The right side panel has no connections or controls.

I must admit…the Tecsun S-8800 has some front panel controls I really appreciate. Most notably, it has a dedicated AM bandwidth selector and fine tuning control. I also like the dedicated treble and bass controls which can also be found on its predecessors’ front panels.

Over the next week, I’ll be evaluating the performance of the S-8800. I plan to post blind audio samples as I’ve done in the past, comparing the S-8800 to other portables: likely the PL-880 and the ICF-7600GR, PL-660 or PL-680.  Please be patient, however, as making these recordings takes time as I like to make sure each radio has a true representative sample and fair shot at showcasing performance.

What about those initial impressions? Yes, I must say I do like the package of the S-8800 better than its predecessors. I like the dedicated IR remote control, the many antenna connections, and, so far, the audio fidelity from the built-in speaker. Makes for a nice package.

But, ultimately, the proof is in the pudding:  let’s put the S-8800 on the air and compare it with some benchmarks!

Follow Tecsun S-8800 posts by bookmarking the tag: S-8800

Making broadcast towers safer for birds

(Source: NPR)

It’s likely the only time you really notice one of your neighborhood broadcast and cell towers is at night when they’re lit up with conspicuous bright red lights.

Those lights help pilots see the huge metal structures that can reach 1,000 feet into the air — but they can spell disaster for birds.

In 1976 in Gun Lake, Mich., one tower killed over 2,300 birds in one night, says Caleb Putnam, who works for the Michigan Department of Natural Resources. He says for reasons scientists still can’t quite figure out, birds kept flying headlong into towers.

“If that many are dying at one night at one tower and yet there are thousands of towers across the country and as you go across the world, the numbers are staggering,” he says.

Putnam says in North America alone it’s estimated that 7 million birds smash into towers every year. But until recently scientists didn’t know why it was happening.

[…]”We were able reduce the numbers of bird fatalities on communications towers by simply extinguishing those non-flashing lights,” she says. “Those fatalities were reduced by as much as 70 percent.”[…]

Click here to listen/read this full report on NPR.

Ajit Pai designated as chairman of the FCC

FCC Commissioner Ajit Pai (R)

(Source: Forbes)

In one of his first official acts, President Trump designated Commissioner Ajit Pai as the new chairman of the Federal Communications Commission. He is the first newly appointed Republican chairman since Kevin Martin nearly 12 years ago. Many have asked: how will the FCC change under Chairman Pai?

Until recent years, the FCC was not a partisan agency. Having served with commissioners Mignon Clyburn and Michael O’Rielly, Chairman Pai is not expected to be particularly partisan.

Chairman Pai has served as a commissioner for nearly 5 years, and his views on a wide range of topics are publicly available on his FCC website that highlights his many Commission opinions, Congressional testimonies, speeches, publications, and blogs.

It is impossible to predict exactly where Chairman Pai will go with specific future policies such as network neutrality, particular mergers, and the aftermath of the disappointing and flawed broadcaster spectrum auction. But it is easy to describe broad themes of a Chairman Pai: follow the law, less regulation, and a folksy approach to government. […]

Continue reading at Forbes.com.