Input Power (dBm): signal power at the input of Stage 1. For RX, enter the received antenna signal; for TX, enter the DAC signal power at the first block input.
Noise bandwidth (MHz): the noise-equivalent bandwidth used for SNR. Enter the bandwidth over which the signal and noise are measured.
Input Noise Floor (dBm/Hz) and Input Noise Temp (K) describe the same source noise. Type into either box; PHP calculates the other using kT. The two values are not added. Noise floor displays two decimal places; calculations and saved files retain full precision.
The default −174 dBm/Hz represents approximately 288.35 K. A 290 K source is −173.98 dBm/Hz. Use the default for a room-temperature source, or enter the antenna noise for your receiving environment.
From SkyNoise, paste Antenna Noise Temp (K) directly into Input Noise Temp, or paste its dBm/Hz value into Input Noise Floor. For example, 30 K gives −183.83 dBm/Hz. Antenna noise temperature is already an equivalent noise-power quantity; use kT without another Planck conversion.
Use antenna noise at the first stage input, including the sky application's antenna/environment contributions. The lineup adds cable, filter and receiver noise separately; do not include those same stages again in the source value.
Type the DAC's total in-band noise density, referred to the first block input, into Input Noise Floor. −150 dBm/Hz is an illustrative example. The K box shows the equivalent noise temperature, not the DAC's physical temperature. Each stage adds its own noise separately; do not add another −174 contribution to the DAC value.
If noise is given in dBc/Hz, add the carrier power in dBm to obtain dBm/Hz. If given as integrated flat noise in dBm, subtract 10 log₁₀(noise bandwidth in Hz). Use the same channel/sideband convention for signal and noise.
Paste the space antenna's equivalent noise temperature from SkyNoise into Input Noise Temp. The antenna's view determines this source noise; the hardware's physical temperature is entered separately for each stage.
All passive blocks use physical temperature automatically, initially 290 K. For a cable, feed or filter before the LNA: enter its gain as negative loss, click its stage header, enter 200 K and its RF frequency in GHz, then save. Its NF is calculated. A passive 1 dB loss at 200 K has approximately 0.71 dB NF; at 290 K it is approximately 1.00 dB.
The antenna noise stays in the input boxes. The 200 K passive stage adds its own thermal noise, then the LNA adds its receiver noise. The passive model uses Planck thermal power at the entered frequency; frequency 0 selects classical kT.
Gain: positive for amplification, negative for loss. NF: for gain blocks, enter measured/specified NF at their actual physical temperature and operating frequency. For passive blocks, NF is calculated from loss, physical temperature and frequency. All NF values use a 290 K reference. Changing source noise does not change this reference.
OIP3 / IIP3 and P1dB / IP1dB are output/input references. Edit either member of a pair; the other follows the gain. Cascaded P1dB and headroom use the reciprocal-sum estimate.
Click Stage N to edit its name, Part No., notes and noise model. New stage temperature fields start at 290 K. Filters, attenuators, variable attenuators, couplers, switches and transmission lines always use the passive physical-temperature model. Enter the RF or IF frequency in GHz; their NF tile is read-only. For an active device, enter specified NF or its measured equivalent input noise temperature; physical temperature alone does not determine its NF. Mixers and IQ converters use measured/specified NF or equivalent input noise temperature, including the device’s channel/sideband convention.
At 290 K, passive NF can be slightly below insertion loss at high frequency because thermal noise includes the Planck correction, while NF uses the fixed kT₀ reference.
Signal level is Input Power plus cascaded gain, in dBm at each stage’s output. The Noise floor row above SNR is total noise density at each stage's output, including amplified source noise and stage-added noise. Save Project records the paired input values and which box was entered; Export ZIP supplies plots, complete tables, CSV and project JSON.