Wireless Signal Strength

The following should help a bit, but understand that FCC data does not get as granular as you might want. They do everything by census block (if any one user in a census block gets signal, they assume the entire census block gets signal).

Spectrum Map version 5!

There isn’t a lot new on the surface for this update. I’ve changed my back-end data source from the now defunct FCC License Viewer to ULS data dumps. A lot went into this effort to completely change how I was downloading and processing the data. It now uses The Cloud(TM) to help in the data processing and file generation.

The result is more data in a more timely manner. I now should support nearly all mobile/cellular licenses that are associated with a market area. Unfortunately, it still doesn’t support point-based licenses for EBS.

The data should be updated on a weekly basis, and be updated without me having to lift a finger.

If you see any issues with the new version of the website, contact me via the contact form!

Posted on November 9, 2019Author anthony Categories Uncategorized

Spectrum Map Notes

Developed by Anthony Fiti (Twitter).

In the newest version of the map (version 5), the data is sourced from the FCC’s weekly transaction files. Previous versions sourced the data from the FCC License View and the FCC’s Spectrum Dashboard. As time moves forward, this data might not be 100% complete or accurate. I make no claim as to the accuracy of this data. If you have a problem with it, double check it with the FCC’s ULS database, then take it up with them.

All names and colors are trademarked/copyright of their respective owners, I take no claim of ownership.

Known Spectrum Map Issues

  • The map does not include Hawaii, Alaska, PR, American Samoa, etc. I left them off because I’m focused on the lower 48. Generally speaking, outside of the lower 48, spectrum isn’t in that desperate of a need because there isn’t sufficient population density to worry about it.
  • In some cases, a license can be divided in terms of both frequency (subdividing a 10MHz chunk of spectrum into two 5MHz pieces for the entire area) or in terms of geography, or both. For example, AWS-1 block E (1740-1745, 2140-2145) Western Region is owned by AT&T, however they let MetroPCS use this spectrum in Santa Barbara County, CA – this is geographical division. My mapping system doesn’t support visualizing the geographic divisions within a license area, so it just looks like they both own that slice of spectrum. Google Maps doesn’t support populating this data at the county level (too many polygons for the browser to handle).


Also . . .

Minimum Signal Strength Needed

What is the minimum signal strength needed for holding a conversation and data exchange over a cellular network? While not as much required as needed for holding a cellular conversation (-100 dBm or so), at least -100 dBm is still required for data transfer to occur while maintaining the 4G or LTE speeds. As the strength deteriorates past that point on to -105 dBm, -110 dBm, -115 dBm, and even -120 dBm, the wireless data transfer speed will become slower.

Carrier Technology Band Frequency
Traditional Cellular 800 MHz & 850 MHz Cellular 824-896 MHz
Traditional PCS 1900 MHz PCS 1850-1990 MH
Carrier Name Band Frequency
AT&T 4G LTE 700 MHz LTE (Lower Band) 710-716 MHz & 740-746 MHz
Sprint 4G LTE 1900 MHZ LTE 1850-1990 MHz
Sprint & Clear 4G WiMAX LTE data Xohm & WiMAX 2.5-2.7 GHz
T-Mobile 3G & 4G AWS (UMTS Band 4) 1700 & 2100 1710-1755 & 2110-2155 MHz
Verizon 4G LTE 700 MHz LTE (Higher Band) 746-757 MHz & 776-787 MHz

Signal Strength Terminology

  • Decibel (db) Link to Wikipedia article → the decibel (symbol: dB) is a dimensionless unit, used for quantifying the ratio between two values, such as signal-to-noise ratio. The db is a relative unit of measurement corresponding to one tenth of a bel (named in honor of telephone pioneer Alexander Graham Bell). It is used to express the ratio of one value of a power or field quantity to another, on a logarithmic scale, the logarithmic quantity being called the power level or field level, respectively. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are often expressed in decibels. Decibel is a unitless fraction, but if set to an arbitrary reference value then add a letter to the end:
    • If reference value is is 1 volt, then the suffix is “V” (e.g., +20 dBV = 100 times higher than one Volt),
    • If the reference value is one milliwatt, then the suffix is “m” (e.g., -20 dBm = 100 times lower than 1/1000th of a Watt).
  • Decibel-milliWatt (dBm) Link to Wikipedia article → is a unit of level used to indicate that a power ratio is expressed in decibels (dB) with reference to one milliwatt (mW) — which is 1/1000th of a Watt. It is used in radio, microwave and fiber-optical communication networks as a convenient measure of absolute power because of its capability to express both very large and very small values in a short form compared to dBW, which is referenced to one watt (or 1000 mW). By comparison, . The dBm is also dimensionless but since it compares to a fixed reference value the dBm rating is an absolute one.
    • +80 dBm is typical transmission power of FM radio station with 50-kilometre (31 mi) range
    • +60 dBm is typical combined radiated RF power of microwave oven elements
    • +33 dBm is maximal device power output from a UMTS/3G mobile phone (Power class 1 mobiles)
    • +27 dBm is maximal device power output from a UMTS/3G mobile phone (Power class 2 mobiles)
    • +24 dBm is maximal device power output from a UMTS/3G mobile phone (Power class 3 mobiles)
    • +21 dBm is maximal device power output from a UMTS/3G mobile phone (Power class 4 mobiles)
    • +15 dBm is typical wireless LAN transmission power in laptops
    • −10 dBm is maximal received signal power of wireless network (802.11 variants)
    • -60 to -75 dBm is roughly 4 to 5 Bars on cell phone (infrastructure power output that reaches phone)
    • -76 to -90 dBm is roughly 3 to 4 Bars on cell phone (infrastructure power output that reaches phone)
    • -91 to -100 dBm is roughly 2 to 4 Bars on cell phone (infrastructure power output that reaches phone)
    • -101 to -110 dBm or is roughly 1 to 2 Bars on cell phone (infrastructure power output that reaches phone)
    • -120 dBm or lower is roughly 0 to 1 Bar on cell phone (infrastructure power output that reaches phone)
  • Gain (dB) – It is a measure of amplification, represented by dB. The higher the dB or the gain, the higher is the amplification achieved by the signal. 0 dB gain means zero gain. 10 dB gain means the signal strength is enhanced by 10 times, 20 dB gain means it is enhanced by 100 times more signal, and 30 dB gain means the signal is enhanced by 1,000 times.
  • Attenuation (dB) – This refers to how much a signal weakens over a distance, or when it passes through construction material. It is measured in dB, and is a negative value. A -10 dB attenuation means the signal is 10 times and a -20 dB attenuation means the signal is 100 times weaker.
  • Antenna gain (dBi) – Antennas have a gain too, represented by the Antenna gain or dBi. This is based on a logarithmic scale. A 0 dBi antenna gain means the antenna cannot hold any signal, 10 dBi antenna gain means that the antenna can receive and transmit 10 times as many signals from the specified direction compared to other directions. a, 20 dBi gain means it is enhanced by 100 times more signal, and 30 dBi gain means the signal is enhanced by 1,000 times.
  • Signal strength (dBm) – The strength of a wireless signal is measured in dBm. dBm is a logarithmic measure.
  • Omni-directional antenna – Refers to an antenna which receives and transmits signals in all directions. Has less antenna gain.
  • Directional Panel antenna – Refers to an antenna which sends and receives signals in just one direction.
  • Radio frequency (RF) – Refers to the frequency used to transmit a wireless radio signal. This can be a Wi-Fi signal, cellular signal, WiFi or just FM and AM radio.
  • RF-EMR – Refers to pulsed, data-modulated, Radio-frequency Electromagnetic Microwave Radiation
  • Downlink signal – Refers to the signal transmitted from the cellular tower to your phone.
  • Uplink signal – Refers to the signal sent from your phone back to the cellular tower.
  • Coaxial cable – Refers to the special type of cable which carries the RF signal. It consists of a conductor at the center made from copper, which is properly shielded. There is also an outer conductor.