Monday, June 29, 2020

Field Day 2020

KL3RR/P QTH BP53gd. East Fork Chulitna river. G5RV jr strung up back in the trees.

Icom IC-7300.  Laptop for WSJT-X and JS8Call digital modes on 10, 20 & 40m.

Wednesday, June 17, 2020

NanoVNA

The NanoVNA is a tiny, self contained, portable, but low cost Vector Network Analyzer.  It features a touch screen and built in lithium rechargeable battery.


NanoVNA with included accessories (minus SMA to UHF adapter).

Of interest to the radio operator is being able to measure reflected power and calculate the Standing Wave Ratio (SWR) over a frequency range.  The NanoVNA automates this resulting in an easy-to-interpret graphical summary of antenna radiation efficiency vs. frequency. 

Hooked up to the Firestik 2MCKB 2m antenna. 

Triangle "1" at 143.400 MHz showing 1.05 SWR.  Should work well on the 2m band 144-148 MHz.

This information is crucial for effective antenna building or diagnosing and many antennas can be adjusted to improve SWR around a desired frequency.

Monday, June 15, 2020

-Hermes-Lite 2 - HF SDR

Minor assembly required.
Hooked up to power, antenna, and ethernet for interface to PC.
The Hermes-Lite can listen on an unlimited number of virtual receivers which can concurrently monitor 4 bands at up to 384 kHz x 4 total bandwidth. 

HF digital modes allow many simultaneous transmissions to fit into a relatively narrow slice of bandwidth. 

The receiving capability of the Hermes-Lite coupled with specialized software and the processing power of the computer allows for monitoring a significant chunk of the HF digital mode frequency range using a single radio. 

SparkSDR - Transmitting on 20m with the built in 5W amplifier and N2ADR filter board. Just over 20 virtual receivers monitoring HF digi modes with one DigiU dedicated to JS8Call.




It is somewhat intensive for the PC and LAN.

I was initially using a 2014-vintage i5 laptop which handled it but was a bit strained and the cooling fans were noisy in that state.  Since then I have switched to a i5-3470 desktop machine which handles it better and with less noise.  I am seeing about 2.5 TB/week (45 Mbit/sec) of data transfer between the HL2 and SparkSDR in the above receiver configuration with 192 kHz sampling bandwidth. The gigabit LAN has plenty of capacity left.

24/7 automated decoding of these signals contributes to an online reporting database allowing visualization of world-wide HF propagation activity:

Pskreporter stats - HL2 with about 20 receivers over a 24 hour period.  Each marker represents a station heard and color denotes the frequency (40m, 30m, 20m, or 17m).  Transmissions between Alaska and Europe travel over the north pole.
On Raspberry Pi 4:

VNC into Raspberry Pi 4 with about 16 receivers (SparkSDR).  Sampling bandwidth 96 kHz. 26 Mbit/s going between HL2 and RPi4.
The Raspberry Pi 4 May be comfortably usable with up to about 4-6 receivers.  Of note is the fact that VNC server uses a significant amount of CPU.  I already disabled the "waterfall summary" for each virtual receiver with some CPU savings, but it seems driving the waterfall graphics adds a significant load especially over a remote connection. 

Sunday, October 6, 2019

-APRS applications

Overlooking Anchorage, Alaska 3510 ft ASL.  Anytone 878-UV transmitting APRS beacon.
On the way up/down some location beacons were not recorded. APRS tracking is limited to where you can be heard by an igate or repeater.  On VHF this is basically line of sight to town.

Sunday, April 28, 2019

-Install/upgrade external antennas, coax into house, & ground system.

Installed lightning rod to power grill Back to the Future style.
-2x galvanized conduit (1 & 1.25" EMT) + hose clamps & exhaust clamp saddle + long ubolt to connect the two sections.  Arrow OSJ 146/440 Mhz J-pole now @ ~30 ft HAAT.

2x Comet CTC-50M window feed-thru jumper with vinyl sliding windows.  Temporary; final setup will go through wall.

Sunday, March 24, 2019

-Raspberry Pi 3 and Mobilinkd TNC2 for APRS duty

  • Setup XASTIR on Raspbian to act as an Igate using Mobilinkd KISS TNC.

XASTIR doing RF -> inet gating.  Terminal highlights commands to activate Bluetooth serial link after paired to Mobilinkd.

Update 6/2020 - Have been running an APRS Igate KL3RR-2 for about 1.5 years. Initially had some issues with bluetooth stability on the Raspi3.  The BT link would fail after a few weeks. I found this was a known issue and solved in the Raspi3 B. Indeed it fixed the problem and now has run stable for many months without any intervention.

Current hardware for KL3RR-2 is a Baofeng UV3R, Mobilinkd TNC2, Raspi3 B running Raspbian and XASTIR.  Antenna is an Arrow J-Pole at approx 30' height.

I appreciate the GUI of XASTIR both for visualization (which is a key outcome of the data produced by APRS) as well as being able to interact and use the station for APRS functions such as messaging.  Coupled with connecting to the raspi via VNC this makes for a functional APRS Igate that is remotely accessible and controllable. 

KL3RR-2 APRS Igate interface via remote connection (VNC).

Sunday, March 17, 2019

-12 Vdc power

Current home setup for powering radio equipment:

Electrical hardware mounted on a cutting board.  Samlex SEC-1230UL 30-A charger, Optima Blue Top 55-Ah battery.  Blue Sea Systems (marine) fuse panel and various other components intended for car audio.
  • The SEC-1230UL is a switch mode supply but quiet enough to not interfere with HF reception.  
  • With the SEC-1230UL and a battery, the system behaves as a dc Uninterruptible Power Supply.
  • With 120 Vac available, the system can maintain a <30 A draw indefinitely (limited by the charger).  However, higher amperages can be sustained intermittently (limited by the battery).

Monday, March 11, 2019

-Mobilinkd

New Mobilinkd TNC 2.2 . Working well so far.  Very quick to setup.  
It links to a tablet, phone, or computer (via Bluetooth) and a radio (via cable).  

The Mobilinkd is a KISS TNC.  It MOdulates/DEModulates between the radio audio in/out and a digital signal sent over the Bluetooth-serial link while facilitating switching of the radio PTT.

The end functionality is completely dependent upon software.  One of the most common uses is for APRS:


Mobilinkd TNC 2.2 w/ Baofeng UV-3R and APRSdroid on a tablet.
The high resolution screen is ideal for mapping APRS data.

The radio and TNC are a compact package.
The Bluetooth is nice as the tablet is not constrained by a physical link to the TNC.

Sunday, February 10, 2019

-DMR hotspot operational

TP-Link TL-WR802N (Travel Wifi AP router) and SharkRF openSPOT 1
Local digital radio internet gateway. 20 mW max output (UHF)

(radio) <-> (openSPOT) <-> (worldwide DMR networks via internet)

-APRS troubleshooting. Anytone 878UV


Anytone AT-D878UV as heard by rtl-sdr+gqrx. Garbled coordinate data in APRS position transmission causes it to be ignored by receiving stations.

A second example showing other stations' APRS traffic for comparison

Update 2/27: Found some information here leading me to a solution for the APRS issue.  Below is a screenshot of my 878 APRS settings which have resolved the unintelligible transmission problem:


Take note of the time delay settings (with red dots) as well as the lack of a coma in "APRS signal path".  These changes resulted in my APRS transmissions clearing up and finally showing up on aprs.fi:

Success!

Update 2020: Updating the CPS and radio firmware to the latest (and matching) versions seems to have eliminated the above issues.  Through the last year I have been using the 878 with to transmit my position in a number of challenging outdoor environments and it has performed and held up well.  Looking forward to APRS messaging capability in the future.

Anytone AT-D878UV DMR & Analog VHF/UHF radio

Sunday, May 24, 2015

Sunday, April 12, 2015

-Portable HF in Alaska

Finished customizing the new protective case:

New setup, Pelican 1495
(Yaesu FT-857D and LDG Z-11 Pro II)

Old setup.  Backpack portable. Chugach Park AK.