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You bring a GPS receiver indoors and it goes blind. The device that locked onto eight satellites in the parking lot can't find one at your desk. If you develop GPS-enabled products, run a timing server, test trackers, or just need a working GPS reference at a bench, this is a daily frustration with a well-understood engineering fix. This guide explains why GPS fails indoors, why the popular quick fixes mostly don't work, and how to build the antenna chain that does: an outdoor antenna, amplification in the right place, filtering, and power delivery over the coax. By the end...

If you work with RF equipment, you've probably spent time connecting and disconnecting antennas, cables, filters, amplifiers, and test equipment. While these routine connections may seem harmless, they can gradually wear out one of the most vulnerable parts of your equipment: the RF connector. A connector saver is a simple, inexpensive adapter designed to protect these connectors from mechanical wear and tear. Despite its simplicity, it can help extend the life of expensive equipment and prevent costly repairs. What Is a Connector Saver? A connector saver is a short RF adapter that remains permanently attached to your equipment's RF port....

A noisy switching regulator on the DC rail of your Low Noise Amplifier will modulate the amplifier's operating point and push noise and spurious content into your signal path. USB power supplies are particularly bad offenders. If you are seeing a forest of spurs that do not correspond to any real signal, check your supply rail on an oscilloscope before you start suspecting your antenna or your filters. The problem is often on the bench, not in the air.     The fix is simple: replace the switching supply with a clean linear regulator that outputs on USB. A battery-backed...

If your AIS receiver seems to be working but you are consistently missing vessels that other stations are seeing, your antenna is probably not the problem. Neither is your SDR dongle or your coax run. The problem is almost certainly something you cannot see on your waterfall at all: FM broadcast interference compressing your LNA before a single AIS packet has a chance to arrive.     This post explains what gain compression is, why FM broadcast is particularly dangerous in coastal environments, and what the attenuation numbers from a real bandpass filter actually mean in practice. What Gain Compression...

  There is a persistent myth in GPS and GNSS system design: more gain ahead of the receiver is always better. Stack enough amplification in front and the problem goes away. It does not work that way. Why Gain Placement Matters GPS signals arrive at the antenna at around -130 dBm, well below the thermal noise floor. The receiver relies on spread-spectrum processing gain to pull the signal out of the noise, not raw signal strength. This is why the LNA's position matters as much as its gain value. Place the LNA close to the antenna and it sets the...