# Tag Info

26

First of all, if you don't want to do any math, then check out a grid square map, such as this one. There is an excellent process at this page, and additional resources from ARRL. Essentially, Grid Squares contain 3 pairs, the first and last letters, and the middle numbers. Longitude is always the first, followed by latitude, for each pair. For simplicity, ...

13

IMO, your question is too general to give a good, specific answer. Also, it would help if you elucidated the motivation for the question. I am a semi-retired electrical engineer, not a security or RF expert but I'll give it a go anyway. The first assumption is that the transmitting equipment is hidden from plain sight and other non radio-related detection. ...

11

Another possibility to look into is meteor burst communication. This is a well-established technology. You beam a VHF signal up into the sky, it bounces off a meteor trail, and your recipient picks up the reflected signal. Since transmission is upwards, picking up the transmitter's location would require being above the transmitter at the time (making ...

8

The story is about Eric LeMarque who got lost after snowboarding out of bounds in the Sierra Nevada mountains. Radio receivers usually contain some kind of oscillator. Detecting the unintentional radiation from the oscillator or the mixing products in the receiver is technically possible, but in modern receivers the power is so weak this power is so weak it ...

8

If you'd like to do it yourself, you can use this Python program I wrote. # -*- coding: utf-8 -*- import sys # Convert latitude and longitude to Maidenhead grid locators. # # Arguments are in signed decimal latitude and longitude. For example, # the location of my QTH Palo Alto, CA is: 37.429167, -122.138056 or # in degrees, minutes, and seconds: 37° 24' ...

7

My first post in SO. Here's a C version... made this for an Arduino project. void calcLocator(char *dst, double lat, double lon) { int o1, o2, o3; int a1, a2, a3; double remainder; // longitude remainder = lon + 180.0; o1 = (int)(remainder / 20.0); remainder = remainder - (double)o1 * 20.0; o2 = (int)(remainder / 2.0); remainder = ...

6

Per this document: Larry E. Price W4RA, the IARU president in 2002, requesting the definitive ITU zone definitions - wrote: You have to keep in mind that the ITU has one administrative purpose for having zones that has nothing at all to do with amateur radio. However, various amateur radio organizations decided to have both awards and operating ...

5

This helped me. For anyone that needs it, here is a port to Java: public class Location { String latlon; String maidenhead; public Location(String p1, String p2) { float lat = -100.0f; float lon = 0.0f; try { lat = Float.parseFloat(p1); lon = Float.parseFloat(p2); maidenhead = latLonToGridSquare(lat, lon); } catch ...

4

Many contests use them as a convenient measure of how many different "regions" you've managed to contact. Since using countries as a contest multiplier isn't necessarily very accurate (within a certain radius, US can only easily reach Canada or Mexico or ocean, within the same radius, a station in central Europe could easily have their first 20 contacts come ...

4

Is this [detection of a receiver through its amplification of received signals] possible in practice? Aaaah, no. Not exactly like described in that thread. In more general terms, yes, it is. So, first of all: the point of radio is that the transmitted energy radiates away from the transmitter. That means that you can't know whether something absorbed that ...

4

at least in the world where I come from Assuming this is the world of arrogant computer security experts (sorry I'm a bit allergic to this): Well, unlike computers, physics wasn't designed by humans. So, any signal that contains significant information needs to contain significant power (that's a direct result of Shannon capacity), and if it has significant ...

3

The Maidenhead locator system (which you correctly tagged) is described in detail in this Wikipedia page. A short summary from that page is: To summarise: Character pairs encode longitude first, and then latitude. The first pair (a field) encodes with base 18 and the letters "A" to "R". The second pair (square) encodes with base 10 and the ...

3

When you fill out the paperwork at the time of taking the test you specify your permanent home address for your license. Thus, if you take the test in California but use a NY address then you will be assigned a call sign appropriate for your license level for New York which uses the 2 zone. Licenses like for a Technician license are issued usually as a 2x3 ...

3

Both are a means of identifying where you are in the world. CQ Zones is managed by CQ Magazine, and the ITU Zones are managed by the ITU. You can see more information about how they are defined in the two questions you linked. Some contests use them as an identifier of where you are, the most notable being the ITU number used in the IARU competition in July, ...

3

I found this reference table on the ITU site: http://www.itu.int/ITU-R/terrestrial/broadcast/hf/refdata/reftables/ciraf.txt That appears to lay out lat/long coordinates for the points outlining the zones. It's linked to from this page titled "Reference Data": http://www.itu.int/ITU-R/terrestrial/broadcast/hf/refdata/index.html

3

I've included Locator based calculations in PyHamTools - an open source python Library, which is easy to use: It's as easy as this: from pyhamtools.locator import calculate_distance, latlong_to_locator locator1 = latlong_to_locator(48.52, 9.375) locator2 = latlong_to_locator(-32.77, 152.125) distance = calculate_heading(locator1, locator2) print("%.1fkm" %...

2

You can start by using a map, but that gets out of hand once you get beyond the second set of digits. There are calculators online, like this one from QRZ or this map-based locator. It's possible to calculate it by hand as well - the Wikipedia article has a good description on how they work. Basically, the first two characters build a grid, just like on any ...

2

There is not any such listing, as the definitions for CQ zones are a bit ambiguous. The official definitions can be found at the CQ Magazine WAZ award definition. Areas like the ocean aren't covered, otherwise it's a fairly simple geography lookup to get the areas defined.

2

I didn't see any answers that had the extended square as referenced in the Wikipedia article. My Clojure implementation (GitHub Gist Here) encodes the fourth and fifth pairs. (defn to-maidenhead [lat long] (let [long (-> long (+ 180) (/ 2)) lat (-> lat (+ 90)) funs [#(* 10 (mod % 1)) #(* 24 (mod % 1)) #(* 10 (mod % 1)) #(* 24 (mod % 1))] ...

2

if by "Grid" you mean "Maidenhead Locator" then here is a similar question, with some sample Python code as answer. The result from the code will be Lon = (start_lon) to (end_lon) Lat = (start_lat) to (end_lat) From that you can easily calculate the "middle" of the square. or you can take the code and adapt, here is the code from the above mentioned ...

2

The Maidenhead system breaks down a grid into increasingly smaller chunks. The fourth pair is defined as an evenly spaced 100 square grid, or 10x10. This site has an excellent image that breaks that down for you: In this picture, the black box outline is MK80ht. You can see this box was further subdivided, and the user's location of Kalpathy, India is ...

1

I remember an episode of the live action TMNT series in which Mike had a pirate radio station. To make detection harder, the transmitter was in his truck. I believe everyone here has been thinking about stationary radio sources so far. By keeping your transmitter moving, and going dark as needed, you may avoid detection for a while longer. They will only be ...

1

There are several techniques. first physically hide the transmitter and antenna. While this is hard for large antennas, it becomes more feasible at higher frequencies. I read a story about a HAM radio fox hunt where the fox (transmitter / antenna) was hidden in a coed's swim suit as she was sunbathing in a park. The hunters knew the transmitter was in the ...

1

A recommendation for a formal definition of the 10 character system is available in the IARU-R1 VHF Handbook. Here's the relevant quote: 3.7 Proposals to Clarify and Standardise the IARU Locator, including higher Accuracy positioning The definition of the existing 8-character scheme should be extended by adding a further division into 24 lettered ...

1

I do a lot of off-network travel and one thing I found out is that you can cache Google Maps as described on this link. Then your Google Maps app will keep running as long as you have GPS (and if you don't you likely have bigger problems).

1

C# version public static String LatLonToGridSquare(double lat, double lon) { double adjLat, adjLon; char GLat, GLon; String nLat, nLon; char gLat, gLon; double rLat, rLon; String U = "ABCDEFGHIJKLMNOPQRSTUVWX"; String L = U.ToLower(); if (double.IsNaN(lat)) throw new Exception("lat is NaN"); if (double.IsNaN(lon)) throw ...

1

Here's the docs on it. http://www.qrz.ru/vhf/qth_h.pdf And of course you were given this one. https://en.wikipedia.org/wiki/Maidenhead_Locator_System Take a look at http://aprs.fi/ http://aprs.fi/page/api

1

The solutions I've seen all seem to be rehashing the same code with little thought to what is actually happening. I decided to write a solution that solves the general case, making it a simple matter to extend the precision of the result to any length. Since I am an iOS developer, the solution is in Swift: private let upper = "ABCDEFGHIJKLMNOPQRSTUVWX" ...

1

Have a Look at numpy.meshgrid http://docs.scipy.org/doc/numpy-1.10.0/reference/generated/numpy.meshgrid.html

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