Fishnet Beacons
Fishnet beacons (Drift Nets, Fishing Buoy Transmitters) are low power transmitters which send periodic identifiers followed by a carrier and long pauses. They are battery powered and use fairly inefficient antenna, yet they can be heard for hundreds or even thousands of miles. Fishnet beacons can be found between 1.6 and 4 MHz, and are very common on the 160-meter band.Despite 'common appearance' on amateur bands, no studies have been conducted so far that would allow us to better understand coverage of fishnet beacons. Unfortunately, amateur radio operators see them as unwelcome signals on “their band”. However, it would be beneficial for amateurs to engage themselves in study of fishnet beacons with aims to provide reception data which would then allow full comprehensive study.
Monitoring fishnet beacons and collecting reception data is both challenging and rewarding. Being able to hear weak signals from a distance presents a technical challenge. The question is: How many (of the thousands of constantly active) beacons can you hear? A few, a dozen, maybe even few hundred? What would be the furthest away beacon that could be heard from your location? Having such information would give you a good idea of how well your radio setup performs on low bands. In addition, your personal reception data, combined with the data from other listeners worldwide, will help to build a larger database. Further analysis will improve our understanding of the propagation patterns on low bands.
Fishnet beacons: The chase is on!
This is a typical spectrum snapshot of 160m band on a winter night on the East coast of NSW, Australia [VK2]. A 100khz span reveals the presence of 6 beacons transmitting simultaneously. A fairly crowded band! Yet don’t be fooled thinking that catching the beacons is effortless. It takes time, patience and luck to identify fishnet beacons – especially if you are using an analog receiver – because the gap between ID’s is between 3-4 minutes.
Model: KTR-18
Power(input): 4W or 10W
Length: 90 cm + 200 cm antenna
For more details on other models, scroll to the bottom of this document.
3 digits:
CLASS 3a
a. (2x1) two letters, one number [ YD3, AY0, VZ8 etc)
4 digits:
CLASS 4a
a. (2x2) two letters, two numbers [ YU46 etc)
CLASS 4b
b. (1x3) one number, three letters [ 4KOW, 4YMZ, 3NRS etc)
5 digits:
CLASS 5a
a. (2x3) two letters, three numbers [ OA837 etc)
CLASS 5b
b. (1x5) one number, four letters [ 2AHBA, 2AHAF etc)
Which beacons from the list of loggings recorded at your location would qualify as EG members? Here are a few simple rules which apply to EG members:
1. The most frequently logged beacon.
For example, a study of VK2DX log reveals that the most often logged ID’s are Class 5b beacons starting with 2Axxx. The most frequent daytime loggers are 2AEGH (1807khz), 2AFYZ (1771khz) and 2ACVW (1753khz). It is therefore reasonable to conclude that 2Axxx beacons would constitute an Endemic Group based on the coast of central part of the state of NSW (VK2). Naturally, a group of beacons with different ID classes might be coexistent in the region.
Finding your local Endemic Group is a crucial building block required to build a global map of fishnet beacons. Getting involved in mapping your local beacons and establishing your EG is the best contribution you can offer as a listener. Even with a very modest setup, this goal can be achieved in a short period of time.
Here is a comparison of two logs from listeners located 110km apart on the NSW coast. Both listeners are using similar equipment (SDR receivers and active Mini-whip antennas).
When the two logs were compared, a number of beacons were recorded by both listeners. This would lead us to believe that these beacons most likely have coverage of at least 50-100km. Naturally, a third participant positioned either South, North or inland would provide even more useful data.
A coordinated listening event which would include a number of listeners from the North of Queensland to as far South as Tasmania, and East to New Zealand, would really help us understand the nature of propagation and the coverage of the beacons in the region.
Catching technique
From a hardware perspective, getting started with fishnet hunting is easy - even a modest radio setup will produce decent results, especially if you are located near the coast.
Most likely you already have what is necessary to get started: a standard HF receiver and a longwire antenna. With bit of patience and persistence, your listening efforts will soon be rewarded.
However if you would like to take it too the next level, you will need a better receiving antenna.
For example, a 160m + 80m duoband vertical or inverted L antenna will provide decent coverage of the fishnet band. If you only have limited space, an active Mini Whip will be more than adequate.
Ultimately, the software defined radio (SDR) receiver will make the chase both exciting and productive. Being able to see the spectrum will give you an almost unfair advantage and your receiving horizon will expand dramatically.
The best listening time is between sunset and sunrise. Winter and early spring / late autumn is the best low band season. Pay attention to weak signals which appear around dusk or dawn - these could potentially be long distance beacons.
If you are located away from the coast, you may not hear as many beacons but your listening reports are still crucial for the long term fishnet study.
Certain frequencies are more fruitful than others - for example, you will catch plenty of signals between 1730-1830 kHz and 2100-2200 kHz.
Below are a couple of snapshots of 2AHAP and 2AFQR next to two ham signals.
Note the strength of their signals!
Sending your listening reports?
Keep your log simple - ID, frequency date and time is sufficient.
The best format for analysis is Excel .xls
Log all signals you hear on a particular day, not just the new ones!
Your contribution to the database is welcome and appreciated:
please email your logs to nick@clockmaker.com.au
73 Nick VK2DX
Appendix I: Log sorted by frequency/date
ID Frequency Date Time VK2DX VK2DDI PH5 1714 07/29/10 X 4QXV 1715 08/14/10 X 3PAA 1715 08/14/10 X 4YVM 1717 08/04/10 X 3YCB 1733 08/14/10 X 3YCB 1733 08/17/10 X TA3 1734 08/17/10 X JH2 1740 08/08/10 X 2ACWX 1740 08/08/10 X 2AEVW 1750 07/26/10 X 3NRS 1750 07/26/10 X YU46 1750 07/26/10 X 3NRS 1750 07/27/10 X 2AEVW 1750 08/04/10 X 3NRS 1750 08/08/10 X YU46 1750 08/08/10 X 3NRS 1750 08/09/10 X YU46 1750 08/14/10 X 2AEVW 1750 08/17/10 X YU46 1750 08/17/10 X UD5 1750 08/17/10 X 2ACWX 1752 07/26/10 X 2ACWX 1752 08/17/10 X 2ACVW 1753 08/04/10 X 2ACVW 1753 08/07/10 X 2ACVW 1753 08/17/10 X 2ACVW 1754 07/26/10 X 2AFVW 1754 07/26/10 X GU1 1755 07/26/10 X GU1 1755 08/01/10 X 2AFAB 1756 08/08/10 X 2AFAB 1756 08/17/10 X 4QVU 1757 08/08/10 X 2AFAB 1757 08/08/10 X 2AFUV 1759 08/17/10 X 2ADOP 1761 07/26/10 X 2AFCD 1763 08/17/10 X OB282 1765 07/26/10 X 2AFWX 1765 08/04/10 X X 2AFWX 1765 08/07/10 X OB282 1765 08/17/10 X CA7 1769 07/26/10 X CA7 1769 08/04/10 X 2AFYZ 1771 07/29/10 X 2AFYZ 1771 07/30/10 X 2AFYZ 1771 08/09/10 X 2AFYZ 1771 08/17/10 X KZ8 1774 08/17/10 X VZ8 1775 07/26/10 X WN9 1775 08/04/10 X 2AFFG 1776 07/26/10 X 2AFFG 1776 08/17/10 X 2AFFF 1776 08/17/10 X 2AHBA 1777 07/22/10 X 2AHBA 1777 08/04/10 X X 2AHBB 1780 08/05/10 X 2AFGH 1780 08/09/10 X 2AHBB 1780 08/17/10 X 2AHBB 1780 08/17/10 X 2ADQR 1783 08/09/10 X AY0 1785 07/22/10 X EO0 1785 07/28/10 X EO0 1785 07/29/10 X TC6 1785 08/04/10 X EO0 1785 08/04/10 X X 2AELM 1786 07/29/10 X 2AHAA 1788 08/09/10 X 2AHAA 1789 07/26/10 X 2AHAA 1789 08/14/10 X 2AHAB 1792 07/29/10 X 2AHAB 1792 07/30/10 X OA837 1793 07/26/10 X OA837 1793 08/04/10 X X OA837 1793 08/09/10 X 2ADRS 1793 08/09/10 X OA837 1793 08/17/10 X 4QRH 1794 08/04/10 X 2AHAC 1795 07/22/10 X 2AHAC 1795 08/04/10 X DK2 1795 08/04/10 X 2AHAD 1798 07/29/10 X 2AHAD 1798 07/30/10 X 2AHAD 1798 08/08/10 X 2AHAD 1798 08/17/10 X 2AHAE 1801 08/04/10 X 2AHAE 1801 08/07/10 X 2AHAF 1804 08/04/10 X 2AHAF 1804 08/07/10 X 2AFMN 1804 08/08/10 X 2AFMN 1804 08/09/10 X 2AHAF 1804 08/17/10 X 2AHAF 1804 08/17/10 X 3TFA 1805 08/07/10 X 2AEGH 1807 07/22/10 X 2AEGH 1807 07/26/10 X 2AEGH 1807 08/17/10 X 2AHAH 1810 08/17/10 X 2AFOP 1811 08/09/10 X 2AFOP 1811 08/17/10 X YR7 1815 08/04/10 X 4QVZ 1817 08/04/10 X 4QVZ 1817 08/17/10 X DL6 1820 07/22/10 X 2AFQR 1820 08/17/10 X 2AHAL 1821 08/04/10 X 2AEAD 1821 08/04/10 X 2AFRS 1822 08/04/10 X 2AFRS 1822 08/04/10 X X 2AHAL 1822 08/07/10 X 2AHAL 1823 07/26/10 X 2AFRS 1824 07/26/10 X 2AFRS 1824 08/05/10 X 2AFRS 1824 08/09/10 X 2AHAM 1825 07/22/10 X 2ABXY 1825 07/27/10 X DF6 1825 08/04/10 X 2ABXY 1825 08/17/10 X 2ABXY 1826 07/26/10 X 2AHAM 1826 07/26/10 X LF9 1828 07/26/10 X 2AHAP 1834 08/09/10 X 2AHAP 1834 08/17/10 X 2ADMN 1840 08/04/10 X 2AEAB 1841 07/26/10 X 2AEAB 1841 08/04/10 X X LA2 1859 07/29/10 X GE0 1865 08/17/10 X DK4 1865 08/18/10 X SK5 1910 08/04/10 X SK5 1910 08/18/10 X TW2 1916 08/17/10 X BT9 1925 08/18/10 X DV7 2002 08/04/10 X AK1 2095 08/17/10 X ZR9 2100 08/17/10 X XR5 2110 08/14/10 X CH5 2110 08/17/10 X XR5 2110 08/17/10 X CH5 2111 08/17/10 X DH4 2113 08/17/10 X CX1 2121 08/17/10 X CX5 2121 08/17/10 X AW9 2130 08/18/10 X JK4 2140 08/09/10 X JK4 2140 08/14/10 X JK4 2140 08/17/10 X YF5 2150 08/18/10 X AFVEE 2153 08/09/10 X TH3EE 2163 08/09/10 X TH3EE 2163 08/14/10 X DM5 2167 08/18/10 X AL7 2175 08/17/10 X UJ2 2180 08/18/10 X XJ0 2423 08/17/10 X JK27 2520 08/04/10 X JK27 2520 08/14/10 X BX1 2534 08/04/10 X EZ5 2541 08/09/10 X EZ5 2542 08/17/10 X GX9 2562 08/09/10 X WR3 2584 08/14/10 X FI1 2587 08/17/10 X FC6 2592 08/17/10 X AA9 2594 08/17/10 X BH4 2599 08/17/10 X CQ8 2614 08/14/10 X NJ8 2664 08/17/10 X KM0 2844 08/09/10 X Appendix II Unique IDs, sorted
alphabetically ID Frequency 2ABXY 1825 2ACWX 1752 2ADMN 1840 2ADOP 1761 2ADQR 1783 2ADRS 1793 2AEAB 1841 2AEAD 1821 2AEGH 1807 2AELM 1786 2AEVW 1750 2AFAB 1756 2AFCD 1763 2AFFF 1776 2AFFG 1776 2AFGH 1780 2AFMN 1804 2AFOP 1811 2AFQR 1820 2AFRS 1822 2AFUV 1759 2AFWX 1765 2AFYZ 1771 2AHAA 1788 2AHAB 1792 2AHAC 1795 2AHAD 1798 2AHAE 1801 2AHAE 1801 2AHAF 1804 2AHAF 1804 2AHAH 1810 2AHAL 1821 2AHAM 1825 2AHAP 1834 2AHBA 1777 2AHBB 1780 3NRS 1750 3PAA 1715 3TFA 1805 3YCB 1733 4QRH 1794 4QVU 1757 4QVZ 1817 4QXV 1715 4YVM 1717 AA9 2594 AK1 2095 AL7 2175 AW9 2130 AY0 1785 BH4 2599 BT9 1925 BX1 2534 CA7 1769 CH5 2110 CH5 2111 CQ8 2614 CX1 2121 CX5 2121 DF6 1825 DH4 2113 DK2 1795 DK4 1865 DL6 1820 DM5 2167 DV7 2002 EO0 1785 EZ5 2541 FC6 2592 FI1 2587 GE0 1865 GU1 1755 GX9 2562 JH2 1740 JK27 2520 JK4 2140 KM0 2844 KZ8 1774 LA2 1859 LF9 1828 NJ8 2664 OA837 1793 OB282 1765 PH5 1714 SK5 1910 TA3 1734 TC6 1785 TH3EE 2163 TW2 1916 UD5 1750 UJ2 2180 VZ8 1775 WN9 1775 WR3 2584 XJ0 2423 XR5 2110 YF5 2150 YR7 1815 YU46 1750 ZR9 2100
The Radio Buoy
KATO, Taiwan
Wenden, Taiwan
Model: KTR-18
Frequency: 1600KHz-2850KHz
Mode : A1A
Power(input): 4W / 10W
Service range: 200 Km
Timing of transmitted code: Standard: Repetition of 30 sec. transmission and 3 min. rest
Battery life: 500 Hrs
Lenght: 90 cm + 200 cm antenna
Gross weight: 22Kg
Dong Yang, Korea
Model: PR-30
Frequency: 1606.5 KHz-2850KHz
Mode : A1A
Power(input): 3W
Service range: 50-150 Km
ID: maximum 4 letters
Timing of transmitted code: Standard: 1 min. transmission and 3 min. rest
Battery life: 720 Hrs
Gross weight: 22Kg
TAIYO Japan
http://www.taiyomusen.co.jp
Frequency: 1600 KHz-4000KHz
Mode : A1A
Power(input): 8W
Service range: 270 Km
Timing of transmitted code: Standard: 1 min. transmission and 3 min. rest
Battery life: 720 Hrs
Gross weight: 21Kg
Blue Ocean Tackle Inc (USA) Distributor
Manufactured by KATO Taiwan
http://www.blueoceantackle.com
Price: USD$995 (excl. battery)
Frequency: 1605 KHz-4000KHz (USA only: 1900-1999, FCC cert)
Mode : A1A
Power: 3W - 8W - 14W
Service range: 400 Km
Timing of transmitted code: ?
Length: 4.3m
Gross weight: 25Kg
New Star (Australian distributor)
http://www.commercial-fishing.net/
Frequency: 1600 KHz-2850KHz
Mode : A1A
Power (input): ?
Service range: 220 Km
Timing of transmitted code: 40 sec emmission 3 min-20 sec pause
Length: ?
Gross weight: 22Kg
Thanks for your interest! Comments are welcome: VK2DXHow does the fishnet beacon look?
A fishnet beacon is a cylindrical transmitter designed to be attached as floating device to drifting fishnets. The main purpose of the beacon is to allow fishing boats to locate their casted fishing nets by means of radio signal detection. Shown here is a selection of beacons manufactured by KATO / Wenden, Taiwan. 
Frequency: 1600KHz-2850KHz
Mode : A1A (Morse code)
Service range: 200 Km
Timing of transmitted code: Standard: Repetition of 30 sec. transmission and 3 min. rest
Battery life: 500 Hrs
Gross weight: 22KgID Transmitting Cycle
The fishnet ID is a call sign which consists of letters and numbers. The distinctive feature of beacon transmission is cyclical, repetitive format in which ID is transmitted. A typical pattern is: – ID – ID – ID followed by 3 minutes non-transmitting interval. One full cycle takes approximately 4 minutes. The ID is transmitted in Morse code at the speed of approximately 15 words per minute.
Beacon ID Format
Endemic Groups - EG
Due to the fact that fishnet beacons do not have a fixed location, finding the exact coverage radius could be a difficult task. The starting point into any distance or location-related analysis would be the establishment of Endemic Groups. An EG is a group of distinctive call signs (ID’s) identifiable at a particular location.
In other words, EG beacons are your local beacons.
2. Audible during daytime.
3. Often logged at the lowest frequency.
The Coverage and Distance Challenge
As previously stated, due to the nature of the beacons (low power, wide frequency range, inefficient antennas) and the large distances that fishermen cover, reception data analysis must be taken very meticulously and cautiously. When comparing two listener’s reports of the same beacon, it is important that the reports were taken simultaneously, or as close in time as possible. Additionally, the more listeners for a given beacon, the more accurate and relevant the information is.
Model: TB-558
Model: KTUS-1L (also KTS1L)
Model: New Star