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!

fishnet beacon

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.

How 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.

fishnet beacon

Model: KTR-18
Frequency: 1600KHz-2850KHz
Mode : A1A (Morse code)

Power(input): 4W or 10W
Service range: 200 Km
Timing of transmitted code: Standard: Repetition of 30 sec. transmission and 3 min. rest
Battery life: 500 Hrs

Length: 90 cm + 200 cm antenna
Gross weight: 22Kg

For more details on other models, scroll to the bottom of this document.

ID 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

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)

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.

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.
2. Audible during daytime.
3. Often logged at the lowest frequency.

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.

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.

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).

fishnet beacon

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!

fishnet beacon fishnet beacon

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

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

 

Appendix III - Manufacturer’s catalogue

The Radio Buoy

fishnet beacon

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

fishnet beacon

http://www.radiobuoy.co.kr/

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
Model: TB-558

fishnet beacon

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

fishnet beacon

http://www.blueoceantackle.com
Model: KTUS-1L (also KTS1L)

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)

fishnet beacon

http://www.commercial-fishing.net/
Model: New Star

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: VK2DX