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Simulcast Fix Guide

Uniden SDS100 Simulcast Fix Guide (2025)

If your SDS100 sounds choppy or garbled on P25, you may be in a simulcast area. This page focuses on practical fixes—antenna choice, placement, and a few safe settings—to help you improve decoding.

Key takeaways (fast answers):
  • Move first: A 3–10 foot position change can dramatically change simulcast decoding.
  • Smaller can be better: For 700/800 MHz public safety, a dedicated 700/800 antenna often decodes cleaner than wideband indoors.
  • Try less signal: Attenuation or a smaller antenna can reduce tower “smearing” and overload.
  • One site helps: If your system has multiple sites, lock onto the site you actually receive best.
Last updated: December 12, 2025
Cite this page: Boy and a Scanner. “Uniden SDS100 Simulcast Fix Guide (2025).” https://boyandascanner.com/sds100-simulcast-guide.html (Updated 2025-12-12)
Related: Complete SDS100 Manual · SDS100 vs SDS150 vs SDS200

What “Simulcast Distortion” Is (Plain English)

Many public-safety P25 systems use multiple transmitters on the same frequencies to cover a wide area. In some locations, your scanner hears more than one tower at once. If those signals arrive out of sync, decoding can suffer—resulting in garbled audio, clipped words, or missed transmissions.

The SDS100 is built for tough simulcast, but your antenna and location still matter a lot.

Quick Fix Checklist (Try in Order)

  1. Move the scanner (window vs interior wall, upstairs vs downstairs). Small changes can pick a single tower more cleanly.
  2. Try a smaller 700/800 antenna for 700/800 MHz systems (less overload, fewer unwanted signals).
  3. Avoid high-gain wideband antennas indoors if they make decoding worse; they can bring in more competing towers.
  4. Try attenuation if you’re close to a tower or you suspect overload (turn it back off if it hurts).
  5. Reduce variables: temporarily disable extra systems and scan only the problem system to evaluate improvements.
Important: A “stronger” signal is not always a “better” simulcast signal. Clean decoding usually means you’re favoring one tower.

Recommended Gear (Simple)

Accessory recommendations are also listed on the homepage shop section.

Frequently Asked Questions

Why does my SDS100 sound garbled on P25 simulcast?

On many P25 simulcast systems, your scanner can receive the same signal from multiple towers at slightly different times. That timing mismatch (multipath) can cause distortion or missed words. The SDS100’s True I/Q design helps, but antenna choice, placement, and a few settings can still make a big difference.

What’s the fastest simulcast fix to try first?

Start with the simplest physical changes: move the radio a few feet, try a smaller 700/800 MHz antenna, and avoid using a high-gain wideband antenna indoors. In simulcast areas, less signal (but cleaner signal) often decodes better.

Should I turn on attenuation for simulcast?

Sometimes. If you’re very close to a tower or your signal is overloaded, attenuation can reduce distortion by lowering the strongest signals. If attenuation makes reception worse, turn it back off—simulcast tuning is highly location-dependent.

Is an 800 MHz antenna better for SDS100 simulcast?

For many public-safety P25 systems on 700/800 MHz, a purpose-built 700/800 MHz antenna can improve decoding because it reduces out-of-band noise and overload compared to a wideband antenna. The best antenna depends on your local bands and setup.

Can the SDS100 monitor encrypted P25 talkgroups?

No. The SDS100 can receive P25 signals, but it cannot decrypt encrypted talkgroups. If your local agencies are encrypted, no scanner will decode that audio.

Next Steps

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