.satellite-calculator-container {
font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
padding: 20px;
background: #f9f9fa;
border-radius: 8px;
border: 1px solid #e0e0e0;
}
.calc-wrapper {
background: #ffffff;
padding: 30px;
border-radius: 8px;
box-shadow: 0 4px 15px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
.calc-header {
text-align: center;
margin-bottom: 25px;
color: #2c3e50;
}
.input-group {
margin-bottom: 20px;
display: flex;
flex-direction: column;
}
.input-group label {
font-weight: 600;
margin-bottom: 8px;
color: #34495e;
font-size: 14px;
}
.input-group input, .input-group select {
padding: 12px;
border: 1px solid #cbd5e0;
border-radius: 6px;
font-size: 16px;
transition: border-color 0.3s;
}
.input-group input:focus, .input-group select:focus {
border-color: #3498db;
outline: none;
box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
}
.btn-calc {
width: 100%;
padding: 14px;
background-color: #2980b9;
color: white;
border: none;
border-radius: 6px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.2s;
margin-top: 10px;
}
.btn-calc:hover {
background-color: #1a5276;
}
.results-box {
margin-top: 25px;
padding: 20px;
background-color: #f1f8fc;
border-left: 5px solid #3498db;
border-radius: 4px;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
align-items: center;
margin-bottom: 12px;
padding-bottom: 12px;
border-bottom: 1px solid #dcebf5;
}
.result-row:last-child {
margin-bottom: 0;
padding-bottom: 0;
border-bottom: none;
}
.result-label {
font-weight: 500;
color: #576574;
}
.result-value {
font-weight: 700;
font-size: 18px;
color: #2c3e50;
}
.article-content {
line-height: 1.6;
color: #444;
}
.article-content h2 {
color: #2c3e50;
margin-top: 30px;
font-size: 24px;
}
.article-content h3 {
color: #34495e;
font-size: 20px;
margin-top: 20px;
}
.article-content ul {
padding-left: 20px;
}
.article-content li {
margin-bottom: 10px;
}
.info-tooltip {
font-size: 12px;
color: #7f8c8d;
margin-top: 4px;
}
@media (max-width: 600px) {
.satellite-calculator-container {
padding: 10px;
}
.calc-wrapper {
padding: 20px;
}
}
function calculateSatThroughput() {
// Get input elements
var bwInput = document.getElementById('sat_bandwidth');
var rolloffInput = document.getElementById('sat_rolloff');
var modInput = document.getElementById('sat_modulation');
var fecInput = document.getElementById('sat_fec');
// Parse values
var bandwidth = parseFloat(bwInput.value);
var rolloff = parseFloat(rolloffInput.value);
var bitsPerSymbol = parseFloat(modInput.value);
var fecRate = parseFloat(fecInput.value);
// Validation
if (isNaN(bandwidth) || bandwidth <= 0) {
alert("Please enter a valid Bandwidth in MHz.");
return;
}
// Calculation Logic
// 1. Calculate Symbol Rate (Rs)
// Formula: Rs = Bandwidth / (1 + Roll-off factor)
var symbolRate = bandwidth / (1 + rolloff);
// 2. Calculate Gross Bit Rate
// Formula: Rb_gross = Symbol Rate * Bits Per Symbol
var grossBitRate = symbolRate * bitsPerSymbol;
// 3. Calculate Net Data Rate (Information Rate)
// Formula: Rb_net = Gross Bit Rate * FEC Rate
var netDataRate = grossBitRate * fecRate;
// 4. Calculate Spectral Efficiency
// Formula: Efficiency = Net Data Rate / Bandwidth
var spectralEfficiency = netDataRate / bandwidth;
// Display Results
var resultBox = document.getElementById('results');
var resSymbol = document.getElementById('res_symbol_rate');
var resEff = document.getElementById('res_efficiency');
var resThroughput = document.getElementById('res_throughput');
resultBox.style.display = "block";
// Formatting output to 2 decimal places
resSymbol.innerHTML = symbolRate.toFixed(2) + " Msps";
resEff.innerHTML = spectralEfficiency.toFixed(2) + " bit/s/Hz";
resThroughput.innerHTML = netDataRate.toFixed(2) + " Mbps";
}
Satellite Data Rate Calculator
Typical transponder bandwidths: 36 MHz, 54 MHz, 72 MHz.
0.20 (20%) – DVB-S2
0.25 (25%) – DVB-S2
0.35 (35%) – DVB-S
0.05 (5%) – DVB-S2X
0.10 (10%) – DVB-S2X
BPSK (1 bit/symbol)
QPSK (2 bits/symbol)
8PSK (3 bits/symbol)
16APSK (4 bits/symbol)
32APSK (5 bits/symbol)
64APSK (6 bits/symbol)
1/4
1/3
2/5
1/2
3/5
2/3
3/4
4/5
5/6
8/9
9/10
Symbol Rate:
0 Msps
Spectral Efficiency:
0 bits/Hz
Net Data Rate (Throughput):
0 Mbps
Understanding Satellite Data Rate Calculations
Calculating the data throughput of a satellite link is a critical task for telecommunications engineers, VSAT technicians, and network planners. Unlike terrestrial fiber optics, satellite bandwidth is a finite and expensive resource defined by the physics of radio waves. This calculator helps determine the maximum usable data rate (Mbps) based on allocated bandwidth and modulation parameters.
Key Parameters in Link Budgeting
To accurately calculate satellite throughput, several factors from the Shannon-Hartley theorem and DVB standards (DVB-S2/S2X) must be considered:
- Allocated Bandwidth (MHz): The slice of the frequency spectrum assigned to the carrier. Common values include 36 MHz or 72 MHz for full transponders, or smaller slices like 5 MHz or 10 MHz for SCPC (Single Channel Per Carrier) links.
- Roll-off Factor (α): In digital communications, pulse shaping filters (like Root Raised Cosine) are used to prevent inter-symbol interference. The roll-off factor determines the excess bandwidth required. Older DVB-S standards typically use 0.35 (35% overhead), while modern DVB-S2 uses 0.20 or 0.25 to save spectrum.
- Modulation Scheme: This defines how many bits are packed into one symbol (signal change). Higher modulation schemes like 16APSK or 32APSK offer higher speeds but require much stronger signal quality (higher C/N) to avoid errors.
- QPSK: 2 bits per symbol (Robust, standard for basic links).
- 8PSK: 3 bits per symbol (Common in DVB-S2).
- 16APSK: 4 bits per symbol (High efficiency, requires good weather/signal).
- FEC (Forward Error Correction): Satellite signals travel 36,000km and are weak upon arrival. FEC adds redundant bits to the stream to allow the receiver to correct errors without retransmission. A rate of 3/4 means for every 4 bits sent, only 3 are data and 1 is error correction code. Lower FEC rates (e.g., 1/2) are more robust but slower; higher rates (e.g., 9/10) are faster but more fragile.
Formulas Used
This calculator utilizes the standard relationship between bandwidth, symbol rate, and information rate:
1. Symbol Rate ($R_s$):
$R_s = \frac{Bandwidth}{1 + \alpha}$
Where $\alpha$ is the roll-off factor.
2. Net Data Rate (Throughput):
$R_{net} = R_s \times M \times FEC$
Where $M$ is the modulation order (bits per symbol) and $FEC$ is the code rate.
Example Calculation
If you lease a partial transponder of 10 MHz using QPSK modulation with an FEC of 3/4 and a standard DVB-S2 roll-off of 0.20:
- Symbol Rate: 10 / (1 + 0.20) = 8.33 Msps
- Gross Rate: 8.33 Msps × 2 bits = 16.66 Mbps
- Net Data Rate: 16.66 Mbps × 0.75 = 12.5 Mbps
This result represents the physical layer throughput available for user traffic (IP packets), though encapsulation overhead (MPEG/GSE) may slightly reduce the final Ethernet throughput.