Wednesday, August 13, 2014

Ham Radio Repeaters Connected via EchoLink

I was testing my radio with some local repeaters and one of the friendly hams said my signal was pretty clear but that he was on EchoLink and couldn't be sure. That reminded me of a question in the Technician class test pool:

"How is access to an IRLP node accomplished?
B. By using DTMF signals"

Then I googled EchoLink and connected my radio. The process is really simple:

1) Enter a frequency (MHz) and tone (Hz) into my ham radio tranceiver
2) Press and hold the push to talk (PTT) button
3) Enter a node number using the keypad
4) Release the PTT button

This "telecommand" controls a  repeater near me to connect across the Internet to a repeater in another city. The remote repeater will announce that is has connected and then I hold my PTT and chat with operators in the remote city.

Apparently I can also download applications and connect directly from a computer or smartphone to a remote repeater. So it's not really even necessary to buy a radio to make use of your license. Things sure have changed since my grandpa showed me how he used his radio when I was young.

For future reference, I listed a few examples of the repeaters nearby and near friends and family.


K5AMM-R Fort Worth  441.675 MHz 110.9 Hz Node 463758
KM5HT-R Hurst ARC 442.850 MHz 110.9 Hz Node 549691
WA5CKF-R Irving 146.720 MHz 110.9 Hz Node 634042
WD5RP-L Arlington, TX 145.560 MHz no tone Node 215788
NB7C-L Boise, ID 902.112 MHz Node 93417
N6MEF-R Santa Clara, CA Node 799194 927.838 MHz 100.0 Hz
KA6TGI-R San Francisco bay Node 68042 144.000 MHz 67.0 Hz
K7LER-R West Seattle Node 4515 441.800 MHz 141.3 MHz
K7RPT-R PORTLAND OR Node 758452 147.380 MHz 100.0 Hz

VA3UN-L Newmarket, ON Node 87273 
442.600 MHZ103.5 Hz
VE3RAK-R Toronto Ont Node 12068 444.700 MHz 103.5 Hz

US Amateur Radio Frequency Allocations for Technician class

The FCC has many regulations related to amateur radio operation and I copied a few notes hare for future reference. As part of my studies, I read FCC part 97 and it's impossible to remember everything. So I found that copying the most relevant regulations helps me quickly access the ones that apply to my Technician class license privileges preferences and location.

Please do your own homework and assume that some of the privileges listed below may not apply. I tried to delete everything about General and Extra class licenses so that I can quickly decide what I am allowed to do.

Source: ARRL

Technician licensees have limited privileges below 30 MHz.

At all times, transmitter power must be the minimum necessary to carry out the desired communications. Unless otherwise noted, the maximum power output is 1500 watts PEP. Technicians are limited to 200 watts PEP on HF bands. Geographical power restrictions apply to the 70 cm, 33 cm and 23 cm bands; see The FCC Rule Book for details.

80 Meters
3.525-3.600 MHz: CW Only

40 Meters
7.025-7.125 MHz : CW only

15 Meters
21.025-21.200 MHz: CW Only

10 Meters
Maximum power 200 watts PEP
28.000-28.300 MHz: CW, RTTY/Data
28.300-28.500 MHz: CW, Phone

28.000-28.070 CW
28.070-28.150 RTTY
28.150-28.190 CW
28.200-28.300 Beacons
28.300-28.500 Phone
6 Meters
50.0-50.1 MHz: CW Only
50.1-54.0 MHz: CW, Phone, Image, MCW, RTTY/Data

50.0-50.1 CW, beacons
50.060-50.080 beacon subband
50.1-50.3 SSB, CW
50.10-50.125 DX window
50.125 SSB calling
50.3-50.6 All modes
50.6-50.8 Nonvoice communications
50.62 Digital (packet) calling
50.8-51.0 Radio remote control (20-kHz channels)
51.0-51.1 Pacific DX window
51.12-51.48 Repeater inputs (19 channels)
51.12-51.18 Digital repeater inputs
51.5-51.6 Simplex (six channels)
51.62-51.98 Repeater outputs (19 channels)
51.62-51.68 Digital repeater outputs
52.0-52.48 Repeater inputs (except as noted; 23 channels)
52.02, 52.04 FM simplex
52.2 TEST PAIR (input)
52.5-52.98 Repeater output (except as noted; 23 channels)
52.525 Primary FM simplex
52.54 Secondary FM simplex
52.7 TEST PAIR (output)
53.0-53.48 Repeater inputs (except as noted; 19 channels)
53.0 Remote base FM simplex
53.02 Simplex
53.1, 53.2, 53.3, 53.4 Radio remote control
53.5-53.98 Repeater outputs (except as noted; 19 channels)
53.5, 53.6, 53.7, 53.8 Radio remote control
53.52, 53.9 Simplex
53.490-53.530 MHz:

2 Meters
144.0-144.1 MHz: CW Only
144.1-148.0 MHz: CW, Phone, Image, MCW, RTTY/Data

144.00-144.05 EME (CW)
144.05-144.10 General CW and weak signals
144.10-144.20 EME and weak-signal SSB
144.200 National calling frequency
144.200-144.275 General SSB operation
144.275-144.300 Propagation beacons
144.30-144.50 New OSCAR subband
144.50-144.60 Linear translator inputs
144.60-144.90 FM repeater inputs
144.90-145.10 Weak signal and FM simplex
145.01,03,05,07,09 are widely used for packet
145.10-145.20 Linear translator outputs
145.20-145.50 FM repeater outputs
145.50-145.80 Miscellaneous and experimental modes
145.80-146.00 OSCAR subband
146.01-146.37 Repeater inputs
146.40-146.58 Simplex
146.52 National Simplex Calling Frequency
146.61-146.97 Repeater outputs
147.00-147.39 Repeater outputs
147.42-147.57 Simplex
147.60-147.99 Repeater inputs

Notes: The frequency 146.40 MHz is used in some areas as a repeater input. This band plan has been proposed by the ARRL VHF-UHF Advisory Committee.

1.25 Meters
222.00-225.00 MHz: CW, Phone, Image, MCW, RTTY/Data

222.0-222.150 Weak-signal modes
222.0-222.025 EME
222.05-222.06 Propagation beacons
222.1 SSB & CW calling frequency
222.10-222.15 Weak-signal CW & SSB
222.15-222.25 Local coordinator's option; weak signal, ACSB, repeater inputs, control
222.25-223.38 FM repeater inputs only
223.40-223.52 FM simplex
223.52-223.64 Digital, packet
223.64-223.70 Links, control
223.71-223.85 Local coordinator's option; FM simplex, packet, repeater outputs
223.85-224.98 Repeater outputs only

The FCC has allocated 219-220 MHz to amateur use on a secondary basis. This allocation is only for fixed digital message forwarding systems operated by all licensees except Novices. Amateur operations must not cause interference to, and must accept interference from, primary services in this and adjacent bands. Amateur stations are limited to 50 W PEP output and 100 kHz bandwidth. Automated Maritime Telecommunications Systems (AMTS) stations are the primary occupants in this band. Amateur stations within 398 miles of an AMTS station must notify the station in writing at least 30 days prior to beginning operations. Amateur stations within 50 miles of an AMTS station must get permission in writing from the AMTS station before beginning operations. The FCC requires that amateur operators provide written notification including the station's geographic location to the ARRL for inclusion in a database at least 30 days before beginning operations. See Section 97.303(e) of the FCC Rules.

70 Centimeters
 420.0-450.0 MHz: CW, Phone, Image, MCW, RTTY/Data

420.00-426.00 ATV repeater or simplex with 421.25 MHz video carrier control links and experimental
426.00-432.00ATV simplex with 427.250-MHz video carrier frequency
432.00-432.07 EME (Earth-Moon-Earth)
432.07-432.10 Weak-signal CW
432.10 70-cm calling frequency
432.10-432.30 Mixed-mode and weak-signal work
432.30-432.40 Propagation beacons
432.40-433.00 Mixed-mode and weak-signal work
433.00-435.00 Auxiliary/repeater links
435.00-438.00 Satellite only (internationally)
438.00-444.00 ATV repeater input with 439.250-MHz video carrier frequency and repeater links
442.00-445.00 Repeater inputs and outputs (local option)
445.00-447.00 Shared by auxiliary and control links, repeaters and simplex (local option)
446.00 National simplex frequency
447.00-450.00 Repeater inputs and outputs (local option)

33 Centimeters
 902.0-928.0 MHz: CW, Phone, Image, MCW, RTTY/Data

23 Centimeters
1240-1300 MHz: CW, Phone, Image, MCW, RTTY/Data

Higher Frequencies:
2300-2310 MHz
2390-2450 MHz
3300-3500 MHz
5650-5925 MHz
10.0-10.5 GHz
24.0-24.25 GHz
47.0-47.2 GHz
76.0-81.0 GHz*
122.25 -123.00 GHz
134-141 GHz
241-250 GHz
All above 300 GHz

* Amateur operation at 76-77 GHz has been suspended till the FCC can determine that interference will not be caused to vehicle radar systems

Tuesday, August 12, 2014

Amateur Radio Technician Class license test study notes

I wanted to share some of my study notes from the Technician Class Amateur Radio license test. There is a lot of information that might be of interest to the geeks out there.

Today I was granted my license from the FCC and my call sign is KG5DMX.

Source: The No-Nonsense Technician-Class License Study Guide (for tests after July 1, 2014)

Note: The complete pool of multiple choice test questions can be found at I also used an Android App called Ham Test Prep to practice answering questions.

Q. What types of international communications are permitted by an FCC-licensed amateur station?

  A. Communications incidental to the purposes of the amateur service and remarks of a personal character

Q. What name is given to an amateur radio station that is used to connect other amateur stations to the Internet?
  A. Gateway

Q. What is the Internet Radio Linking Project (IRLP)?

  A. A technique to connect amateur radio systems, such as repeaters, via the Internet using Voice Over Internet Protocol For more reliable long-distance communications, amateurs use the HF frequencies.

For more reliable long-distance communications, amateurs use the HF frequencies. UHF signals are often more effective from inside buildings than VHF signals because the shorter wavelength allows them to more easily penetrate the structure of buildings. (T3A02)

horizontal antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands. (T3A03)

The primary advantage of single sideband over FM for voice transmissions is that SSB signals have narrower bandwidth. (T8A07)

The approximate bandwidth of a single sideband voice signal is 3 kHz. (T8A08)

The approximate bandwidth of a VHF repeater FM phone signal is between 10 and 15 kHz. (T8A09)

Morse Code, or CW, is the type of emission that has the narrowest bandwidth. (T8A05)

The approximate maximum bandwidth required to transmit a CW signal is 150 Hz. (T8A11)

International Morse is the code used when sending CW in the amateur bands. (T8D09)

All of these choices are correct when talking about instruments used to transmit CW in the amateur bands (T8D10):

Straight Key
  Electronic Keyer
Computer Keyboard

Some modes have very wide bandwidths. The typical bandwidth of analog fast-scan TV transmissions on the 70 cm band, for example, is about 6 MHz. (T8A10)

The type of transmission indicated by the term NTSC is an analog fast scan color TV signal. (T8D04)

Digital modes: packet, PSK31 When hams talk about “digital modes,” we are talking about modes that send digital data rather than voice or other types of analog signals, such as television. Usually, we connect our transceivers to a computer to modulate and demodulate the digital signals, but some newer transceivers can do this internally.

All of these choices are correct (examples of a digital communications method) (T8D01):


Packet radio was one of the first digital modes. It is called packet radio because the data to be sent from station to station is separated into a number of packets which are then sent separately by the transmitting station and received and re-assembled by the receiving station.

All of these choices are correct when talking about what may be included in a packet transmission (T8D08):

  A check sum which permits error detection
  A header which contains the call sign of the station to which the information is being sent Automatic repeat request in case of error

Some amateur radio digital communications systems use protocols which ensure error-free communications. One such system is called an automatic repeat request, or ARQ, transmission system. An ARQ transmission system is a digital scheme whereby the receiving station detects errors and sends a request to the sending station to retransmit the information. (T8D11)

APRS is one service that uses packet radio. The term APRS means Automatic Packet Reporting System. (T8D02)

A Global Positioning System receiver is normally used when sending automatic location reports via amateur radio. (T8D03)

Providing real time tactical digital communications in conjunction with a map showing the locations of stations is an application of APRS (Automatic Packet Reporting System). (T8D05)

A popular digital mode on the HF bands is PSK. The abbreviation PSK means Phase Shift Keying. (T8D06)
PSK31 is a low-rate data transmission mode. (T8D07)

The “31” in PSK31 comes from the fact that data is transmitted and received at about 31 baud and that the bandwidth of a PSK31 signal is only about 31 Hz.

Separate eight-foot long ground rods for each tower leg, bonded to the tower and each other is considered to be a proper grounding method for a tower. (T0B08)

When installing devices for lightning protection in a coaxial cable feedline, ground all of the protectors to a common plate which is in turn connected to an external ground. (T0A07)

The maximum power level that an amateur radio station may use at VHF frequencies before an RF exposure evaluation is required is 50 watts PEP at the antenna. (T0C03)

the human body absorbs more RF energy at some frequencies than at others. (T0C05)

The 50 MHz band has the lowest Maximum Permissible Exposure limit. (T0C02)

To reduce RF current flowing on the shield of an audio cable (or in a power supply cable), you would use a ferrite choke. (T4A09)

Flat strap is the type of conductor that is best to use for RF grounding. (T4A08)

One thing that would reduce ignition interference to a receiver is to turn on the noise blanker. (T4B05)

Another common setting on VHF/ UHF transceivers is the offset frequency. This is especially important when operating repeaters. The common meaning of the term “repeater offset” is the difference between the repeater’s transmit and receive frequencies. (T4B11)

Many, if not most, new amateurs buy a hand-held transceiver, usally called an “HT,” as their first transceiver. One disadvantage of using a hand-held transceiver is that the maximum output power is generally only 5 W, and because of this, they have limited range. To increase the low-power output of a handheld transceiver, and therefore its, range, you can use an RF power amplifier. (T7A10)

Operating Procedures FM Operation Once they get their licenses, most Technicians purchase a VHF/ UHF FM transceiver. This type of radio allows them to use repeaters and participate in public-service events. A repeater station is the type of amateur station that simultaneously retransmits the signal of another amateur station on a different channel or channels. (T1F09)

Auxiliary, repeater, or space stations amateur stations can automatically retransmit the signals of other amateur stations. (T1D07)

To use repeaters, you need to know how to set up your radio. Repeaters receive on one frequency and transmit on another. You program your radio so that it receives on the repeater’s transmit frequency and transmits on the repeater’s receive frequency. The difference between the transmit frequency and receive frequency is called the repeater frequency offset. Plus or minus 600 kHz is the most common repeater frequency offset in the 2 meter band. (T2A01)

Plus or minus 5 MHz is a common repeater frequency offset in the 70 cm band. (T2A03)

Repeater operation is called duplex operation because you’re transmitting and receiving on two different frequencies. When the stations can communicate directly without using a repeater, you should consider communicating via simplex rather than a repeater. (T2B12)

Simplex communication is the term used to describe an amateur station that is transmitting and receiving on the same frequency. (T2B01)

To help amateurs operating simplex find one another, frequencies on each band have been set aside as “national calling frequencies.” 446.000 MHz is the national calling frequency for FM simplex operations in the 70 cm band. (T2A02)

146.52 MHz is the national calling frequency for FM simplex operation in the 2 m band.

Because repeaters often operate in environments where there is a lot of interference they are programmed not to operate unless the station they are receiving is also transmitting a sub- audible tone of a specific frequency. These tones are sometimes called PL (short for “private line”) tones or CTCSS (short for “continuous tone-coded squelch system”) tones. CTCSS is the term used to describe the use of a sub-audible tone transmitted with normal voice audio to open the squelch of a receiver. (T2B02)

If your radio has not been programmed to transmit the proper sub-audible tone when you transmit, the repeater will not repeat your transmission.

All of these choices are correct when talking about common problems that might cause you to be able to hear but not access a repeater even when transmitting with the proper offset: (T2B04)
  • The repeater receiver requires audio tone burst for access
  • The repeater receiver requires a CTCSS tone for access
  • The repeater receiver may require a DCS tone sequence for access

One of the controls on a VHF/ UHF transceiver is the squelch control. Carrier squelch is the term that describes the muting of receiver audio controlled solely by the presence or absence of an RF signal. (T2B03)

Saturday, August 9, 2014

Google Boosts Secure Sites in Search Results

This is great news! Google adjusted their ranking algorithms to favor (ever so slightly) sites that support HTTPS.

Source: Google via Electronic Frontier Foundation

"... we’d like to encourage all website owners to switch from HTTP to HTTPS to keep everyone safe on the web."

Wednesday, August 6, 2014

Rosetta arrives at comet destination

Source: ESA via Space Fellowship

NavCam animation 6 August. Copyright ESA/Rosetta/Navcam

“After ten years, five months and four days travelling towards our destination, looping around the Sun five times and clocking up 6.4 billion kilometres, we are delighted to announce finally ‘we are here’,” says Jean-Jacques Dordain, ESA’s Director General.

“Europe’s Rosetta is now the first spacecraft in history to rendezvous with a comet, a major highlight in exploring our origins. Discoveries can start.”
“Over the next few months, in addition to characterising the comet nucleus and setting the bar for the rest of the mission, we will begin final preparations for another space history first: landing on a comet,” says Matt.
“Arriving at the comet is really only just the beginning of an even bigger adventure, with greater challenges still to come as we learn how to operate in this unchartered environment, start to orbit and, eventually, land,” says Sylvain Lodiot, ESA’s Rosetta spacecraft operations manager.
“After landing, Rosetta will continue to accompany the comet until its closest approach to the Sun in August 2015 and beyond, watching its behaviour from close quarters to give us a unique insight and realtime experience of how a comet works as it hurtles around the Sun.”