Digital Modem Engineer
Posted Aug 19, 2026 · We last checked this listing on Sep 20, 2026
Likely interview questions for this role
Written from this job description, not a generic list. Each one notes what the interviewer is really checking.
Behavioral
Tell me about a time you had to choose between spectral efficiency and latency in a modem design. What did you pick and why?
real-world judgment on engineering tradeoffs versus textbook knowledge
Describe a channel model you've built for a real link. What assumptions did you make, and how did you validate that the model matched what you saw on real hardware?
rigor in connecting simulation work to physical reality, a recurring failure point in DSP roles
Tell me about a time your algorithm design had to change because the digital design or firmware team told you it wasn't feasible in silicon or in the given area/power budget.
collaboration skill and willingness to adapt algorithms to implementation constraints
Technical
Walk me through how you'd design a transmit pulse shaping filter when the whole point of the system is to shave off every possible microsecond of latency.
whether the candidate understands the tradeoff between filter length, ISI control, and group delay in a latency-obsessed design
How do you approach carrier and symbol clock offset recovery when you can't afford the acquisition time of a long training sequence?
depth of hands-on experience with fast-acquisition synchronization schemes, not just textbook PLL theory
Compare blind equalization, training-based, and decision-directed approaches. When would you actually pick one over the others for a low-latency link?
whether the candidate has actually implemented these, not just studied them academically
When you move an algorithm from floating point to fixed point for RTL implementation, what tends to break first, and how do you catch it before it becomes a hardware bug?
practical fixed-point design experience versus theoretical familiarity
What's your process for going from a link-level simulation in Python or MATLAB to something you'd hand off for RTL sign-off?
whether the candidate has actually shipped a design end-to-end versus only doing research-stage work
Have you worked directly with RF or microwave hardware limitations, like oscillator phase noise or amplifier nonlinearity, and how did that change your digital design choices?
cross-domain awareness between RF front end and digital modem design, called out as a bonus but relevant to real link performance
Situational
Suppose your point-to-point wireless link is losing lock intermittently under fading conditions. How would you go about isolating whether it's carrier tracking, symbol timing, or equalization at fault?
structured debugging approach across the receive chain rather than guessing
If you had to cut latency by another 10 percent on an existing modem architecture that's already been tuned hard, where would you even start looking?
seniority and instinct for where marginal latency gains actually hide in a mature system
This role requires reliable, predictable availability given how the wireless network operates. Tell me about a time you had to be responsive to a production issue outside normal hours.
honesty about commitment to on-call type demands tied to trading infrastructure uptime
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