DEV Community: Alex Mages

Hertzbel, JavaScript's First Frequency and Decibel Conversion Library

Alex Mages — Fri, 21 Aug 2020 15:21:31 +0000

A few weeks ago, my company started working on a new project for the satellite communications market. While I looked over user stories and tech requirements, I realized that there were no useful JavaScript libraries built to handle frequency conversions or decibel calculations.

I quickly set out to make an all-in-one library that my company, my industry, and general users can call from to handle all those tricky (and sometimes painful) decibel and frequency calculations. Thus I present Hertzbel, JavaScript's first frequency, and decibel conversion library.

Negatronic / hertzbel

hertzbel

Installation

npm add hertzbel or yarn add hertzbel

Introduction

hertzbel is a javascript library created to handle frequency related calculations and conversions, and a comprehensive of decibel calculations.

In telecommunications, frequencies and decibels go hand in hand. In the frequency domain, using decibel logarithmic formulas in place of Volts or Watts allows observers to see very high power levels and minuscule power levels on the same graph. To learn more about the usefulness of decibels visit wikipedia

The Hertzbel library was designed specifically to be used with spectrum analyzer data, though these calculations will assist in any relatable fields.

Changelog

1.1.0: added toFixed
1.0.5: removed restriction to number of decimals
1.0.3: added convertFrequency to Hertz
1.0.0: initial launch of Hertzbel.

Hertz Functions

Hertzbel has several frequency related calculations. Users may enter a string or a number as parameters into the functions.

Note: strings must be

…

View on GitHub

Hertz

Hertzbel can take a frequency string and convert it to another frequency, add two frequencies together, subtract frequencies, multiply frequencies with integers, and divide with integers.

Frequency Conversion

Translate any frequency from Hz, kHz, MHz, GHz, THz to another.

note that values entered must be strings or numbers. Numbers will be considered to be in Hz base units.

Example 1 `toMegaHz({string | number})`

import {toMegaHz} from "hertzbel";
toMegaHz("1 GHz");
-> "1000.000000 MHz"

A couple of things to take note of here:

toMegaHz can accept any combination of "1 GHz" (e.g., "1ghz", "1GHz", "1 GHZ ")
Depending on the to function, values will always show to Hz.
the ToHz functions series can be strung together to work with other hertzbel calculations.

Example 2 `toTeraHz({string | number})`

import {toTeraHz} from "hertzbel";
toTeraHz("101 MHz");
-> "0.000101000000 THz"

In this example, I went to an extreme only to convey how cleanly hertzbel handles frequency conversions.

The complete list of toHz functions is:

ToHz()
ToKiloHz()
ToMegaHz()
ToGigaHz()
ToTeraHz()

Frequency Addition

Add any two frequencies together. The leading parameter will determine the resulting units.

note that values entered must be strings or numbers. Numbers will be considered to be in Hz base units.

Example 1 `addFreq({string | number}, {string | number})`

import {addFreq} from "hertzbel";
addFreq("10khZ", 1001);
-> "11.001 kHz"

As mentioned before, hertzbel will handle any frequency string as long as it has the right spelling.
Using a number will force hertzbel to assume it is in Hz
Note the returned value gives values down to the Hz

Example 2 `addFreq({string | number}, {string | number})`

import {addFreq} from "hertzbel";
addFreq("10 MHz", "1 GHz");
-> "1010.000000 MHz"

Frequency Subtraction

Subtracts one frequency from another. The leading parameter will determine the resulting units.

Example `subFreq({string | number}, {string | number})`

import {subFreq} from "hertzbel";
subFreq("10760 MHz", "1500 MHz");
-> "9260.000000 MHz"

Frequency Multiplication

Multiples a frequency against an integer

Example `multFreq({string | number}, {number})`

import {multFreq} from "hertzbel";
multFreq("500 Hz", 50);
-> "25000 Hz"

Frequency Division

Divides a frequency against an integer

Example `divFreq({string | number}, {number})`

import {divFreq} from "hertzbel";
divFreq("3000 MHz", 401)
-> "7.481297 MHz"

Stringing Frequency Functions

Hertzbel allows users to string frequency functions.

Example 1

User wants to divide 3000 MHz by 601 then convert that value to kHz

import {toKiloHz, divFreq} from "hertzbel";
toKiloHz(divFreq("3000 MHz", 601));
-> "4991.681 kHz"

Example 2

User wants to add three frequencies together: 100 kHz, 250 kHz, and 450 kHz.

import {addFreq} from "hertzbel";
addFreq(addFreq("100 kHz", "250 kHz"), "450 kHz"))
-> "800.000 kHz"

Decibel

The second piece of the hertzbel library is decibel conversion. RF, satcom, and other types of engineers have to convert power from Watts to decibels and back periodically.

Hertzbel offers a simple way to perform dB conversions (though it is limited to Watts currently).

From Watts to Decibels

Translates values from any Watt to any decibel. Users may enter a string or number as parameters into the function. Numbers will be considered to be in mW.

Example 1 `toDbm({string | number})`

import {toDbm} from "hertzbel";
toDbm("20 mw");
-> "13 dBm"

Example 2 `toDbuw({string | number})`

import {toDbuw} from "hertzbel";
toDbuw("1W";
-> "60 dBuW"

The complete list of toDb is:

toDbuw()
toDbm()
toDbW()

From Decibels to Watts

Converts values of any decibel to any Watt. Users must use a string.

Example 1 `toW({string})`

import {toW} from "hertzbel";
toW("40 dbuw");
-> "0.01 W"

Example 2 `toMw({string})`

import {toMw} from "hertzbel";
toMw("-3 dbm");
-> "0.5011 mW"

The complete list of toW is:

toUw()
toMw()
toW()

Download

Try out hertzbel instantly in your JavaScript app, just download with npm add hertzbel or yarn add hertzbel and start making something. View the npm library here hertzbel.

Conclusion

As a member of the Satcom community, I sincerely hope more libraries like hertzbel will appear in the open source ecosystem for newer languages.

The JavaScript language is very conducive to writing fast code; it is widely supported, and extremely easy to configure. I, for one, feel like its time to start pushing Satcom software in a new direction, and hopefully, hertzbel will help start the transition.

Using TLE.JS Library for Satellite Position and Dish Pointing

Alex Mages — Mon, 10 Aug 2020 14:52:41 +0000

Earlier last year I, blew the dust off my satellite communication textbook and attempted to write a dish pointing app for my company that's in the satellite communications realm.

I quickly discovered that the math was involved, and after several days of exhausting math and Python code writing, I came up a (barely) usable app:

Negatronic / dish-pointer

Parabolic Dish Pointing software

dish-pointer

the dish-pointer project a rough protoype of the equations required for Parabolic Dish Pointing software for GEO satellites.

Getting Started

the dish-pointer should work on all OS that support Python 3.6

Requirements

main.py was written in Python 3.6, and has the following dependecies:

Package	Description	Version	Install
matplotlib	Graphing and math Library	3.03	pip install matplotlib

Installing

Included in the project is a pip freeze of the needed libraries. To install requirements using pip freeze

1. Open Command Line
2. cd to where dish-pointer project is cloned
3. Enter "pip install -r dish-pointer_pip_freeze.txt

Exectuion

To run main.py

1. Open Command Line
2. cd to where dish-pointer project is cloned
3. python main.py

Example Operation

Enter Earth Station Longitude, for West use '-': -97.33
Enter Earth Station Latitude, for South use '-': 37.68
Enter Satellite subpoint Longitude, for West use '-': -123
Antenna azimuth is 218.2°
Antenna look angle 38.7°

…

View on GitHub

Recently, I came back to this project wanting to port it over to a React app and dreaded refactoring the math, that is, until I discovered Two-Line Elements(TLE) set and the tle.js library.

What is TLE

According to wikipedia.org the two-line element is

... a data format encoding a list of orbital elements of an Earth-orbiting object for a given point in time, the epoch. Using suitable prediction formula, the state (position and velocity) at any point in the past or future can be estimated to some accuracy.

below is an example TLE of the International Space Station

ISS (ZARYA) 1 25544U 98067A 20220.25765183 .00031791 00000-0 57938-3 0 9999 2 25544 51.6453 95.7043 0001117 20.0719 119.8247 15.49172948239931

TLEs give a series of mathematical numbers to plot the orbit of the space object, which can be utilized to find the predicted Latitude and Longitude (among other things).

TLE's can be obtained from multiple sites such as celestrak.com space-track.org, and other websites.

What is TLE.js

During research for my web application, I discovered the TLE.js library. TLE.js is a JavaScript library that processes the tle data with easy to use functions.

davidcalhoun / tle.js

🛰️ Satellite TLE tools in JavaScript: get lat/lon of satellites, get look angles, plot orbit lines, extract individual TLE elements, etc

tle.js

Satellite TLE tools in JavaScript

Installation

npm add tle.js or yarn add tle.js

Introduction

tle.js is designed to simplify satellite TLEs and SGP4 with a friendly interface, with satellite.js doing the heavy lifting behind the scenes.

The origin of TLEs goes back to the punchcard days! A TLE, or two-line element set, is used by SGP4 propagators to determine spacecraft positioning information, taking into account gravity perturbations (the moon, etc).

Most users will probably want to simply get the latitude/longitude of a satellite (see getLatLngObj) or get the look angles from a ground position, which can be used to track where in the sky a satellite is visible (see getSatelliteInfo). Users may also want to plot orbit lines (see getGroundTracks).

Users may also be interested in grabbing specific values from a TLE. In this case, you can use one of the TLE getters, for…

View on GitHub

TLE.js Example 1: Satellite Position

Installation

npm install tle.js or yarn add tle.js

Import

in our index.js file import getLatLngObj

const { getLatLngObj } = require("tle.js/dist/tlejs.cjs");

Usage

create a constant of a string

const { getLatLngObj } = require("tle.js/dist/tlejs.cjs");

const tle = `ISS (ZARYA)
1 25544U 98067A   17206.18396726  .00001961  00000-0  36771-4 0  9993
2 25544  51.6400 208.9163 0006317  69.9862  25.2906 15.54225995 67660`;

then console log the results

const { getLatLngObj } = require("tle.js/dist/tlejs.cjs");

const tle = `ISS (ZARYA)
1 25544U 98067A   17206.18396726  .00001961  00000-0  36771-4 0  9993
2 25544  51.6400 208.9163 0006317  69.9862  25.2906 15.54225995 67660`;

console.log(getLatLngObj(tle));

Console Log:

{ lat: 32.69293160995973, lng: -164.48496742284183 }

Note in our example Lng is a negative value; this means the satellite is currently in the Western Hemisphere, a positive value means would mean it is in the Eastern Hemisphere. If the Lat value is negative, then the satellite is in the Southern Hemisphere, if positive then the Northern Hemisphere.

const { getLatLngObj } = require("tle.js/dist/tlejs.cjs");

const tle = `ISS (ZARYA)
1 25544U 98067A   17206.18396726  .00001961  00000-0  36771-4 0  9993
2 25544  51.6400 208.9163 0006317  69.9862  25.2906 15.54225995 67660`;

let satPos = getLatLngObj(tle);
let lat = "N";
let lng = "E";

if (satPos.lat < 0) {
  lat = "S";
}
if (satPos.lng < 0) {
  lng = "W";
}
console.log(
  "Latitude: " + Math.abs(satPos.lat) + " " + lat + ", " + "Longitude: ",
  Math.abs(satPos.lng) + " " + lng
);

Console Log

Latitude: 50.59794614813468 N, Longitude:  91.89917475916603 W

TLE.js Example 2: Dish Pointing

To get azimuth and elevation directions from tle.js, use getSatelliteInfo(). getSatelliteInfo() variables are getSatelliteInfo(tle, optionalTimestamp, observerLat, observerLng, oberserverElevation) note that the timestamp is optional.

Grab the desired lat/long coordinates of the observer site, and paste into the correct constants.

const { getSatelliteInfo } = require("tle.js/dist/tlejs.cjs");

const tle = `ISS (ZARYA)
1 25544U 98067A   17206.18396726  .00001961  00000-0  36771-4 0  9993
2 25544  51.6400 208.9163 0006317  69.9862  25.2906 15.54225995 67660`;

const observerLat = 37.709203;
const observerLng = -97.427754;

run getSatelliteInfo(). If not using optionalTimestamp enter null, if on the ground enter 0 for elevation.

const { getSatelliteInfo } = require("tle.js/dist/tlejs.cjs");

const tle = `ISS (ZARYA)
1 25544U 98067A   17206.18396726  .00001961  00000-0  36771-4 0  9993
2 25544  51.6400 208.9163 0006317  69.9862  25.2906 15.54225995 67660`;

const observerLat = 37.709203;
const observerLng = -97.427754;

console.log(getSatelliteInfo(tle, null, observerLat, observerLng, 0))

Console Log

{
  lng: -103.77041233731748,
  lat: 48.083145374941935,
  elevation: 11.084527491294315,
  azimuth: 337.91719541768254,
  range: 1357.0378375655516,
  height: 393.729417250428,
  velocity: 7.679154118414166
}

lng is the longitudinal position of the satellite
lat is the latitudinal position of the satellite
elevation is the dish's pointing elevation
azimuth is the dish's needed direction to point the satellite

getSattelliteInfo() doesn't take in consideration the line of sight of the dish, and whether the satellite is observable for that use getVisibleSattelites().

Conclusion

By utilizing the tle.js library, modern engineers can quickly deploy web or mobile applications that can track satellites, provide satellite dish look angles, and provide a list of visible satellites. With just a bit of searching
you can find great libraries, like tle.js, that significantly reduce the headache and time spent on small components of much larger projects.

DEV Community: Alex Mages

Hertzbel, JavaScript's First Frequency and Decibel Conversion Library

Negatronic / hertzbel

hertzbel

Installation

Introduction

Changelog

Hertz Functions

Note: strings must be

Hertz

Frequency Conversion

note that values entered must be strings or numbers. Numbers will be considered to be in Hz base units.

Example 1 toMegaHz({string | number})

Example 2 toTeraHz({string | number})

Frequency Addition

note that values entered must be strings or numbers. Numbers will be considered to be in Hz base units.

Example 1 addFreq({string | number}, {string | number})

Example 2 addFreq({string | number}, {string | number})

Frequency Subtraction

Example subFreq({string | number}, {string | number})

Frequency Multiplication

Example multFreq({string | number}, {number})

Frequency Division

Example divFreq({string | number}, {number})

Stringing Frequency Functions

Example 1

Example 2

Decibel

From Watts to Decibels

Example 1 toDbm({string | number})

Example 2 toDbuw({string | number})

From Decibels to Watts

Example 1 toW({string})

Example 2 toMw({string})

Download

Conclusion

Using TLE.JS Library for Satellite Position and Dish Pointing

Negatronic / dish-pointer

Parabolic Dish Pointing software

dish-pointer

Getting Started

Requirements

Installing

Exectuion

Example Operation

What is TLE

What is TLE.js

davidcalhoun / tle.js

🛰️ Satellite TLE tools in JavaScript: get lat/lon of satellites, get look angles, plot orbit lines, extract individual TLE elements, etc

tle.js

Installation

Introduction

TLE.js Example 1: Satellite Position

Installation

Import

Usage

TLE.js Example 2: Dish Pointing

Conclusion

Example Code

Negatronic / tle-example

Example 1 `toMegaHz({string | number})`

Example 2 `toTeraHz({string | number})`

Example 1 `addFreq({string | number}, {string | number})`

Example 2 `addFreq({string | number}, {string | number})`

Example `subFreq({string | number}, {string | number})`

Example `multFreq({string | number}, {number})`

Example `divFreq({string | number}, {number})`

Example 1 `toDbm({string | number})`

Example 2 `toDbuw({string | number})`

Example 1 `toW({string})`

Example 2 `toMw({string})`