Norway has had its fair share of precipitation this winter. Along the coast most of it has been in the form of rain. But that is different in the mountains. Our cabin at 800 m above sea level is now about to disappear in the snow and we can hardly see out of the windows anymore. This is a result of having had to shovel the snow off the roof three times so far this winter. And there is yet more to come.

They say that one has to go back to the winter of 1958 for more snow than we have had this winter, and we are still only in February. The snow has also given us an unexpected problem. Our digital TV signal is now gone.

The TV transmitter is at Mount Gaustadtoppen at 1883 m ASL which is about 10 km to the North and with almost free line of sight. It used to be possible to receive the signals from the national TV provider (Riks-TV) with just a simple indoor dipole, i.e. two wires each of length 13-14 cm connected to a coaxial cable. But not so anymore after all the snow has accumulated outside the windows.

Therefore I had to find a good Yagi-antenna calculator and make a better antenna. I put it on a cardboard of length 45 cm and used the antenna calculator of K7MEM (Martin Meserve). It is a little hard to figure out the exact frequency as there are 5 multiplexes in the TV system and for that particular transmitter they range from 506 to 620 MHz (http://www.finnsenderen.no/finnsender). I therefore just designed the antenna for the multiplex in the middle, 563 MHz. The wavelength is 53.3 cm and typical antenna element length is half of that.

The antenna calculator gave me a design with one reflector behind the receiver element, and four directors in front of it. In the picture, the reflector is to the left and the antenna points to the transmitter to the right.

I made the elements from thick wire, and just taped them to the cardboard. The connector to the coaxial cable is under the cardboard and attached to the center of element two from the left – the one which is split into two.

The Yagi antenna was first described by H. Yagi in the paper “Beam Transmission of Ultra Short Waves“, (Proceedings of the Institute of Radio Engineers, 1928). But as the contribution from his colleague Uda was at least as great as Yagi’s, the antenna should really be called the Yagi-Uda antenna. I seem to remember that Uda could not write English (both of them were Japanese), so the article was written in the name of Yagi only.

But what about my Yagi, eh Yagi-Uda antenna, did it work? Yes, actually it did! With digital signals there is a threshold effect and above a certain signal level the signal quality quickly goes to 100% with a low BER (bit error rate) and with this antenna I came above that threshold. The gain of this antenna is in the order of 8 dB or about 6 dB more than the old single element antenna. Luckily, that was enough to compensate for the attenuation through the snow pile. And as you can see, one doesn’t need aluminium to make a working TV antenna.

[In Norwegian:  Verste snøvinter i manns minne og en innendørs TV-antenne]

Data recorded from an RTL-SDR USB dongle with the SDR# program using the Apowersoft Free Online Screen Recorder.

Related posts:

• “Car keys in the 70 cm band” (with more documentation of hardware and software)
• “Not so busy 70 cm ISM band”

Yesterday’s post entitled “Car keys in the 70 cm band” showed a very busy band around 433.92 MHz with up to 10 simultaneous transmissions. That snapshot was taken on a Sunday afternoon at 16:32 local time. Here is a much less crowded snapshot taken with the USB SDR-RTL dongle under the same conditions as the previous blog post. The difference is that this is from late Monday night at 23:34 local time:

Press image for a larger view

Thanks to all viewers who have made the former blog post the most popular on my blog for this week. Thanks also to the RTL-SDR blog which gave it publicity in the blog post “Looking at the 432 to 438 MHz ISM band“.

Related posts:

• “Car keys in the 70 cm band”
• “Video of busy 70 cm ISM band due to car key fobs”

Press image for a larger view

Related posts:

• “Not so busy 70 cm ISM band” showing the status on a late Monday night
• “Video of busy 70 cm ISM band due to car key fobs“

How do the cheap Baofeng handhelds compare? I have had the Baofeng UV-5R since I bought it from the 409shop in April 2012, but recently I noticed that the UV-B5, UV-B6, and UV-82 have appeared on the market also. If I should need another handheld transceiver for VHF/UHF, is there any advantage in getting any of the other models?

I prepared the following table in order to highlight differences and similarities. Bold characters signify an improvement for what I conceive to be typical radio amateur use.

Feature	UV-5R	UV-82	UV-B5
Front-end	OK	OK	Improved
Antenna	Short	Longer	Longer
Signal meter	On/off	On/off	Dynamic
Squelch	VHF: On/off UHF: Tiny steps 21. Dec 2013	As the UV-5R 21. Dec 2013	Larger steps
Size and shape	Square and small	Fits better in hand, larger buttons	Fits better in hand
Frequency/channel change	Up/down	Up/down	Rotary encoder
VFO/MR button	Yes	Turn radio off, then press menu as you turn it on 3. Jan 2014	Yes
Band button	Yes	No (in menu)	Switches  automatically
Dual PTT button	No	Yes	No
Programming	Need a computer to enter alpha tags	Alpha tags  can be entered  from keyboard	Alpha tags can  be entered  from keyboard
Memory channels	128	128	99 + 16 for FM radio
Display	7 characters in name	7 characters  in name	Harder to read, only 5 characters in name
Modifications	Enlarge mic hole, (and here), Low modulation mod	–	Unused button as background light switch

This post was updated on June 4, 2022, after the summit house construction was completed.

Perhaps this should be called The Slacker’s Guide to Activating Pikes Peak since I am going to describe the easy way to do a Summits On The Air (SOTA) activation on America’s Mountain. If you plan to hike up, you have my complete support but this post is not meant for you.

Pikes Peak (W0C/FR-004) is about 10 miles straight west of downtown Colorado Springs. See the Pikes Peak website for useful tourist information. At an elevation of 14,115 feet, the mountain towers over Colorado Springs and the other front-range cities. (You may see the elevation listed as 14,110 but it was revised upward in 2002 by the USGS.) This means that it has an excellent radio horizon to large populated areas. On VHF, it is possible to work stations in Kansas, Nebraska, Wyoming and New Mexico. See VHF Distance From Pikes Peak  and Pikes Peak to Mt Sneffels. On HF, you’ll do even better.

Getting There

Access to the summit has three options: hike up, drive up via the Pikes Peak Highway or ride the Pikes Peak Cog Railway. Most people will probably choose the highway since the cog rail only gives you 30 to 40 minutes on the summit. (Normally, you return on the same train that takes you to the top. You can try to schedule two one-way trips but that is a challenge.)

After a few years of turmoil and construction, the summit of Pikes Peak is now back to operating normally but with some changes. The new summit house/visitors center is open and it is a beautiful new facility. The Cog Railway is also operational with brand new equipment. There is a new boardwalk that allows easy strolling on the summit and improved views near the edge of the summit.

Pikes Peak Highway

The highway is at a well-marked exit off Highway 24, west of Colorado Springs. There is a “toll” to use the highway (~$15 per person, check the Pikes Peak Highway website for the latest information and a $2 discount coupon.) Starting in 2022, you must have a reservation (2-hour window) to drive to the summit (roughly Memorial Day to Labor Day). The specifics are likely to change, so be sure to check the Drive Pikes Peak page for the latest updates.

The road is paved all of the way to the top and is usually in good shape. The only caution on driving up is that some people get freaked out by sections of the road that have steep drop-offs without guard rails. It is very safe, but some folks can’t handle it. The main caution driving down is to use low gear and stay off your brakes. There are plenty of signs reminding you to do this and during the summer there is a brake check station at Glen Cove where the rangers check the temperature of your brakes.

It takes about an hour to drive to the summit, assuming you don’t dawdle. It is best to drive up during the morning and avoid the afternoon thunderstorms.

On The Summit

The W0C Association Reference Manual (the SOTA rules for Colorado) used to suggest a “qualifying hike” of 100 vertical feet but this item has been removed from the manual. If you decide to do such a hike, I suggest you proceed down Barr Trail which is the main hiking trail coming up from the east side of the peak. Do not try to walk along the road, as the rangers will stop you. The trail starts on the east side of the summit house (towards Colorado Springs) and is marked with a sign. You have to cross over the cog rail tracks to get to it. (Please try to avoid getting run over by the train as it scares the tourists and makes a mess.)

The summit of Pikes is broad, flat and rocky, so pick out a spot away from the buildings for your SOTA adventure. There are quite a few radio transmitters on the peak so expect some interference. Since this is way above treeline, your antennas will have to be self-supporting. For VHF, giving a call on 146.52 MHz FM will usually get you a few contacts and sometimes a bit of a pileup. Be aware that on top of Pikes you are hearing everyone but they can’t always hear each other. It can get confusing. Another VHF simplex frequency worth trying is 146.58 MHz (The North America Adventure Frequency).   On the HF bands, pray for good ionospheric conditions and do your normal SOTA thing.

Your body and your brain will likely be moving a little slower at 14,000 feet due to the lack of oxygen. Don’t be surprised if you have trouble deciphering and logging callsigns. Take it slow and monitor your physical condition on the peak.

Bring warm, layered clothes, even in the summer, since Pikes Peak can have arctic conditions any time of the year. Keep a close eye on the weather since thunderstorms are quite common during the summer months. Lightning is a very real danger, so abandon the peak before the storms arrive.

73, Bob K0NR

Resources

SOTAwatch web site
W0C SOTA Website
Pikes Peak Tourist Information
Pikes Peak (W0C/FR-004) SOTA Page
Pikes Peak Webcams

The post How To Do a SOTA Activation On Pikes Peak appeared first on The KØNR Radio Site.

When you measure the energy out of a GSM cell phone at the moment of initiating a call, you get the picture to the right. It shows the first 15 seconds.

For the first 3.5 seconds there is the signalling between the phone and the base station. Then the connection is established, but after some time (at 4.2, 5.6, 7.5 and 9.5 seconds) one can see how the phone turns the power down, according to the commands it gets from the base station.

The first example was for the case of a strong received signal, all bars are shown in the signal strength meter. The reduction in power, preservers battery life and as a side effect the user is exposed to a smaller amount of radiation. Interestingly, one can see that after a while there is a small adjustment of the power and it is turned up a bit (at 11.5 seconds).

In other cases one can see a situation which follows the same pattern in time, except that the power stays at a high value. This second recording was done in my basement where GSM coverage is much poorer. Here the phone’s signal level indicator hardly shows any signal.

The third plot is a zoom of the previous one. Here one can see how the phone only transmits 1/8 of the time as it shares the channel with 7 other phones in a time multiplex. It is allowed to transmit every 4.6 ms and this is the reason why one often can hear a buzzing sound at 1/4.6 ms = 217 Hz in equipment which is placed close to a phone.

One also sees another frame structure, as the phone transmits 25 bursts and then breaks for one burst before continuing. Every transmission consists of 150 bits, but that is not possible to resolve with the simple setup that was used here.

The equipment was a dipole antenna and a simple diode detector:

• A half wave dipole antenna for 950 MHz has a length of 0.5*3*10⁸/950*10⁶ = 15.8 cm, thus the antenna is about 2 x 8 cm (probably not very critical). The antenna was made from stiff self-supported wires.
• There is a resistor of R=1 kohm across the antenna and then a Shottky diode which acts as a detector (A Shottky diode which handles higher than 1 GHz is needed and BAT46 was used here), and finally a 1000 pF capacitor as a filter.